“A Vintage Phone In 2020 - Hackaday” plus 1 more

“A Vintage Phone In 2020 - Hackaday” plus 1 more


A Vintage Phone In 2020 - Hackaday

Posted: 14 Jan 2020 12:00 AM PST

When we make a telephone call in 2020 it is most likely to be made using a smartphone over a cellular or IP-based connection rather than a traditional instrument on a pair of copper wires to an exchange. As we move inexorably towards a wireless world in which the telephone line serves only as a vehicle for broadband Internet, it's easy to forget the last hundred years or more of telephone technology that led up to the present.

The iconic British telephone of the 1960s and 1970s, the GPO model 746. Mine is from 1971.
The iconic British telephone of the 1960s and 1970s, the GPO model 746. Mine is from 1971. (That isn't my phone number)

In a manner of speaking though, your telephone wall socket hasn't forgotten. If you like old phones, you can still have one, and picture yourself in a 1950s movie as you twirl the handset cord round your finger while you speak.

As we move inexorably forward, it's worth considering for how much longer we'll be able to do this. If all goes well, I'll be receiving a new fibre optic connection in a few weeks. Along a sliver of glass will come faster Internet that I can currently dream of, and I'm expecting that the box that our telephone provider puts on the end of it will have a telephone socket that is simply the front-end of a dedicated VOIP client. It'll undoubtedly work with my digital answerphone, but will it still work with a 50-year old model with an old-fashioned dial designed for use with a mechanical Strowger exchange? If I'm going to have to hack on this old phone, I'd better figure it out now in case I have to hook it up to something else to keep it communicating.

Just How Does A Telephone Work?

A grotesquely simplified schematic of a dial phone. In this diagram SW2 is open and SW3 is closed, so the handset is off the cradle but the dial is not in use..
A grotesquely simplified schematic of a dial phone. In this diagram SW2 is open and SW3 is closed, so the handset is off the cradle but the dial is not in use.

The great thing about a passive device whose roots lie around the turn of the twentieth century is that its principles are relatively easy to understand. A phone like my GPO 746 contains a lot of clever circuitry to give it better audio, and to protect it from line faults, over-voltage, and other mishaps. But its most basic operation can be explained with something like the much-simplified schematic we've pictured.

On the left is the handset, with a carbon microphone and an earpiece in series. When the handset is off the cradle, SW3 is closed, and because the line has a standing DC voltage on it a current flows through the handset. Any audio on the line is heard in the earpiece, and any speech into the carbon microphone varies that current and creates an audio signal in return.

A telephone dial, front and rear. Daderot [CC0]
A telephone dial, front and rear. The two sets of spring contacts can be seen, on the left the one for pulse dialing and on the right the one that switches in the low resistance across the handset. The speed governor is diagonally across the mechanism, and the toothed wheel that drives it also serves to operate the left hand contact. Daderot [CC0]
When the handset is put on its cradle SW3 is opened and there is no DC current path, but through the capacitor C1 there is an AC path to the bell B1. Thus the exchange can ring the bell by sending an AC voltage on top of the DC standing voltage.

SW1 and SW2 are the contacts in the dial, and since it has become a viral meme that people below a certain age may be unfamiliar with dial phones it's worth explaining the operation of the dial for them. A spring loaded disk is rotated to a point representing the desired number by the user before being let go. It returns at a constant rate set by a governor, and as it does so it closes a set of contacts here labelled SW2 to switch in a low resistance across the handset, and it passes its other contacts, SW1, over a toothed wheel. The effect is to interrupt the line current and create a series of pulses set by the number dialed, which were originally used in a mechanical exchange to advance the switchgear a step with each pulse.

An interesting side-effect of this circuit is that with some telephones it was possible to simulate dialing by rapidly depressing the cradle in sequence. On some payphones this offered a means to circumvent the coinbox circuit which disabled the dial. (I remember some students at my university getting into trouble for doing this.) Who needs a 2600 Hz tone to scam the telco!

The Other Side Of The Socket

Having understood our telephone, how might we simulate a telephone line to connect it to? I sat down for an evening in the hackerspace with my GPO 746 to find out.

My basic fake phone line simulator, which should serve as a template for something a little more useful.
My basic fake phone line simulator, which should serve as a template for something a little more useful.

A web search will tell you that a phone line carries a standing DC voltage and an intermittent AC voltage to operate the bell. Further searching reveals that each of those voltages can be 50 V, and that the DC current shouldn't be more than 50 mA. A good place to start therefore is with a bench power supply set to 50 V, and a 1 kΩ resistor to limit the current and simulate the resistance of several miles of phone cable. With the resistor in place any change to the line can only cause a 50 mA current to flow, and thus the possibility for damage is reduced. Connecting this to the 746 resulted in the sound picked up in the microphone being audible in the earpiece, and had I wanted to I could have retrieved the audio after the 1 kΩ resistor.

Experimenting with driving a dial phone on the bench.
Experimenting with driving a dial phone on the bench.

Similarly, with the handset on the cradle I could apply an AC voltage and ring the bell. My AC transformer was a bit less than 50 V, but it did work with smaller volume. I still lacked any means of sensing dialing or the cradle, for which I needed to sense the presence or absence of 50 mA DC current. The real GPO exchange back in the day would have done this with a relay in series with the line, so I reached for a small relay. At this point I learned that relays have a hysteresis curve on their close and release currents so it was not as reliable or as quick as I'd hoped. I began to understand why telecoms circuits use reed relays. In the future I'll have to use a current sensing resistor and a transistor to do the job.

To make this work as a real project, I will have to pay attention to my two 50 V power supplies with probably a little boost converter and oscillator to produce my AC bell drive, and then I'll need to program a microcontroller to handle being on-hook and off-hook, as well as decoding the pulse streams into numbers. I may also have to pay attention to the phase relationship between my audio source and the audio from the microphone, as feedback can become a problem in some circumstances. Once I have mastered those things I'll be able to make a unit that sits behind a standard British Telecom master socket and provides a connection to anything I choose, be it a GSM module or a SIP client on a single board computer. In that way I can still be using my GPO 746 dial phone in decades to come.

Working from home, keeping connected: 17 video conferencing and collaboration tools to consider - www.computing.co.uk

Posted: 23 Mar 2020 12:00 AM PDT

The coronavirus outbreak is spreading chaos and anxiety around the world, causing businesses and individuals to reassess in a fundamental way how they are going to keep going over the coming weeks and months. One tiny sliver of comfort is that our internet-enabled connectedness has opened up new ways of doing things, allowing parts of the workforce to operate remotely, thus helping to slow the spread of the virus as well as enabling activity to continue in a way that would not have been possible even five years ago.

For those employees able to work from home, audio and video conferencing can help reduce the sense of isolation that many are feeling, providing an all-important psychological boost as well as helping them plan and order their work. Conferencing tools provide today what telephone did a generation ago: a vital link between individuals, family members, friends and colleagues.

The tools featured here can all help businesses to keep their employees and partners connected and supported through audio and video. Some are heavyweight, integrated enterprise unified communications and collaboration (UCC) systems. Others are consumer-oriented point solutions, which may suffice for smaller teams.

With the advent of the crisis, some vendors have loosened their restrictions, allowing more people to join, permitting longer meetings or expanding the free tier for certain types of business.

It's important to pick a tool that meets the organisation's needs. Requirements will vary widely from sector to sector and across the size spectrum. Here is a checklist of some of the features and factors you should consider when selecting a conferencing tool for homeworkers.

Features to consider

  • Supported OSs and platforms
  • Pricing / free trial
  • Support options / service guarantees
  • Ease of use
  • Performance and availability, especially when bandwidth is limited and/or demand is high
  • Web client /  browser support
  • Instant messaging
  • Moderator controls
  • Admin dashboard
  • Live or post-meeting transcription
  • Screen sharing
  • File sharing
  • Meeting recording facility
  • HD audio/video
  • Voice over IP (VoIP)
  • Number of simultaneous connections allowed
  • Time allowed per meeting
  • Encryption
  • Identity and Access Management (IAM) options
  • Cloud storage
  • Locale settings for various languages

Delta

Delta is Computing's technology market intelligence services that distills the opinions and experience of thousands of IT leaders. We have put together a special three month trial for access to all research to help with business continuity at this challenging time. For the price of a cup of coffee per team member day. Conditions apply. Click here to request a demo.

Image source: Microsoft
Image source: Microsoft

Microsoft Teams

Microsoft Teams evolved out of Skype for Business. It offers VoIP calls, video and audio conferencing and chat. It was designed to compete with Slack and also features Slack-like chatrooms called channels.

Teams is integrated with Office 365 Word, Excel, PowerPoint, OneNote, Planner, Power BI and Delve as well as its cloud storage and sharing services such as SharePoint.

Users can record meetings and group calls and upload them to storage in Azure. There's an option for automatic transcription so that users can playback recordings with closed captions.

Clients are available for Windows, macOS, iOS, and Android and there's a beta for Linux desktops.

Teams comes bundled as a paid-for option with Office 365 with pricing starting at £3.80 per user per month. There is also a free version. Users without an O365 subscription can sign up for a free 6-month trial of the online office suite.

Delta respondents were positive about Teams' ease of use. "O365 has helped get UC products onto users' desktops for little cost," said one, while another commented that end users' familiarity with Microsoft products at home "makes business use simpler". However, the licensing model was not popular, with multiple users complaining about excessive complexity between versions and implementations.

Skype could be an adequate solution for small teams of up to 20 employees. It is free to use unless you want to make calls to landlines and mobiles.

Image source: Cisco
Image source: Cisco

Cisco Webex

Cisco Webex is a cloud-based collaboration suite which includes Webex Meetings, Webex Teams and Webex Devices. Webex provides core collaboration capabilities, including video meetings, team messaging and file sharing. The suite is suitable for small group collaboration as well as enterprise-wide deployments. Webex is accessible from the browser, via desktop/mobile app or and also on some video devices

Delta respondents appreciated the solution's reliability, feature set, integration, technical support and ease of use. However, the licensing model was said to be confusing and some felt Cisco was a little too keen to push its (paid-for) training and support services.

Cisco offers a 30-day free trial of Webex Meetings supporting up to 200 participants. Cheapest of the paid-for plans, Starter covers up to 50 participants, 5GB of cloud storage and up to nine host licenses and is priced at £11.25 per month per host. More expensive options allow a larger number of participants, more hosts and storage and add 24/7 support.

Cisco is offering Webex free of charge during the Covid-19 crisis: "Your free Webex Meetings plan gives you meetings with 100 participants, HD video, screen sharing, and a personal room. Use it as long as you like," the company says.

Image source: Zoom
Image source: Zoom

Zoom

Fast-growing Zoom offers a scalable video conferencing platform which it claims can accommodate up to 1,000 video participants and 10,000 viewers. Forty-nine videos can be broadcast simultaneously on-screen, allowing multiple participants to share their screens at the same time. Meetings are end-to-end encrypted and Zoom offers role-based user security.

The free Basic plan is limited to 100 participants and 40 minutes, whereas £11.70 per host per month buys the Pro version where the time limit is extended to 24 hours and cloud storage offered. The Business and Enterprise versions include auto-generated transcripts, an on-premises option, managed domains, dedicated support, company branding and other additions.

Clients are available for most platforms including Linux and there are plugins for Chome browser and Outlook.

Image source: Fuze

Fuze

Formerly known as ThinkingPhones, Fuze is a cloud-based integrated enterprise collaboration platform that includes audio and video conferencing as well as chat, VoIP, voicemail and messaging. It's designed primarily for organisations with 250+ employees. Fuze facilitates HD audio and video conferencing for meetings with up to 1,000 participants including screen and content sharing. There's also a presence function that integrates with Outlook and Google calendars so colleagues can when others are available.

The Fuze app is available for Windows, macOS, Chrome OS, or Ubuntu and other Debian-based Linux distributions with Android and iOS apps provided. Fuze integrates with Office365 and Chrome. There is also a web-based version of Fuze called Fuze Web which requires the use of Chrome browser.

Fuze plans start at £17.00 per user per month - there is no free tier.

Avaya
Image source: Avaya

Avaya Team Collaboration

Avaya Team Collaboration enables voice, video and persistent group chat with integrated document storage and task management. The software is sold on a monthly or annual subscription model and is priced on a per-subscriber basis with prices starting at £6.00 per user per month. There is a free tier but it doesn't include group video.

Delta respondents felt Avaya Team Collaboration was a solid choice although some remian worried about its financial stability, the company having filed for Chapter 11 bankruptcy four years ago. Of more concern was the lack of integrations: "Integration with bespoke systems do not work, although it was sold on the basis that it would," said one.

The company recently launched Spaces an "app [that] integrates web meetings and team collaboration, creating a cloud workspace in which messaging, meeting, sharing content, and managing tasks from a browser or mobile device is all possible."

Avaya is allowing free use of Spaces to educational and non-profit organisations worldwide until 31 August 2020.

Mitel MiTeam Meetings
Image source: Mitel

Mitel MiTeam Meetings

MiTeam Meetings is Mitel's integrated video conferencing and collaboration suite. It features complete 16-person multi-pane viewing and screen and file sharing plus collaborative whiteboard sessions. All meeting activities are archived in the cloud by default.

The app MiTeam is compatible with Windows, macOS, iOS and Android devices.

Pricing is not available on the website, but there's a 6 month free trial for qualifying customers of the Mitel MiCollab enterprise collaboration suite.

Delta respondents appreciated the progress made since the company acquired Shoretel in 2017, saying it had allowed the company to make a fresh start. "The system is intuitive, well supported and any issues are resolved quickly. The mobile client works on most mobile platforms", said one. But others criticised Mitel for being too hardware-centric and said that after-sales support was lacking. 

Image source: LogMeIn
Image source: LogMeIn

LogMeIn GoToMeeting / Join.Me

GotoMeeting comes in versions designed for small, medium and large organisations. Features include screen sharing, conference calling, integrated VoIP conference calls, videoconferencing, mobile conferencing, meeting recording and transcription. There are plugins for O365, Google Calendar and Salesforce.

Prices start at £9.50 per month for 150 people.

GoToConnect bundles the GoToMeeting virtual meetings software with the Jive VoIP virtual phone suite.

Join.me is a simple screen sharing and video conferencing solution designed with ease of use in mind. It is targeted at smaller organisations and features screen sharing, audio, video, whiteboard and chat.

Join.me prices start at £9.00 per month for up to 5 participants per meeting and with no webcam streams, but an unlimited number of meetings are allowed and there's also no limit on duration.

There are separate rates for non-profits for whom £10.00 per month buys facilities for 50 meeting participants, 10 videos and screen share.

Delta respondents said LogMeIn products were "simple to use", "easy to set up" and "good for end users". On the other hand, some felt scalability was weak. They also picked out training, cost of ownership, ongoing improvement and hidden costs as areas for improvement.

LogMeIn has said it will allow critical frontline workers to use GoToMeeting for free for 3 months.

RingCentral
Image source: RingCentral

RingCentral Meetings

RingCentral Meetings is a cloud-based video conferencing service that unifies HD video conferencing, mobility and web meetings for up to 100 participants. Functionality can be expanded with addons: Webinar, Large Meetings, RingCentral Rooms and RingCentral Rooms Connector.

The main features of RingCentral Meetings include HD video conferencing, audio dial-in access, screen-sharing, multi-point video conferencing, video gallery, spotlight speaker and integrated chat.

The RingCentral userbase among Delta respondents was small. The company recieved positive comments for ease of use and deployment, but it was said by others to be aggressively sales-led and rather US-centric.

Prices start at the UK equivalent of $14.99 per user per month for up to 100 participants and unlimited group meetings.

In response to the Covid-19 emergency, RingCentral is offering free access to RingCentral Office to "all healthcare providers, schools (K-12), and non-profit organisations who are new customers."

Atos Unify
Image source: Atos

Atos Unify Circuit

Unify is Atos SE's communications and collaboration brand, specialised in developing and deploying unified communications, network infrastructure & security and managed/professional services for small and large businesses.

Circuit is an app the provides voice, video, screen share, chat and file sharing.

A basic implementation of Circuit is available for free, with 1GB storage. It supports 100 users and up to three users per conference call. The Team package is designed to meet the needs of small groups. It offers 5GB of storage and up to six users per conference call, with an unlimited number of users. It also features SLA support and costs £2.95 per user per month. Professional and Enterprise packages are available for more complex organisations.

Atos Unify also provides OpenScape Cloud, a Unified Communications as a Service (UCaaS) offering. It is based on Circuit and voice communication platform OpenScape Voice.

Recently the company announced it would be using RingCentral as its preferred provider of UCaaS solutions. The two companies will introduce a co-branded UCaaS solution as part of the Atos Digital Workplace offering.

Delta users found the product to be fully featured and easy to use, although reliability could be a problem especially with the mobile apps, and support was patchy due to it being outsourced to third-parties.

Alcatel-Lucent Rainbow
Image source: Alcatel-Lucent

Alcatel-Lucent Enterprise Rainbow

Rainbow is Alcatel-Lucent Enterprise's cloud-based Unified Communications and Collaboration (UCC) solution.

It is best suited to large organisations looking to make the most of existing assets such as PBXs and provides a single control pane across various services. It is designed for fast integration with PBX solutions workstream collaboration and CPaaS.

Rainbow's main features include contact management, presence, chat, audio/video call and screen and filesharing. It uses WebRTC to ensure high-quality audio and video streams in the browser. Rainbow uses NLP to offer transcription services, intelligent routing, and speech and text analysis.

Delta respondents said ALE solutions are easy to set up and scale and that support is good. On the downside, others felt the company was still hidebound by its PBX past and was not innovating quickly enough.

Rainbow is also an open platform-as-a-service offering, with a set of APIs enabling users to integrate the solution's collaboration tools into their existing in-house applications and business processes.

There is a limited free tier. Pricing for more advanced options is available on request.

3CX WebMeeting
Image source: 3CX

3CX WebMeeting

3CX is an open-platform software VoIP phone system that works with IP phones and SIP trunks both on-premise or in the cloud. 3CX WebMeeting is a clientless web conferencing and collaboration solution which uses WebRTC to offer video calls. The usual file and screen sharing features are also supported.

It's available as a small Linux appliance for $200, as a free Windows VM or as a hosted cloud-based PBX service.

The standard version of 3CX is free and allows web conferences for up to 25 participants. Additional features including O365 and CRM integration and call recording are available in Enterprise which costs from $1.31 per user per month.

Delta users appreciated 3CX's clear pricing and low costs, although documentation and particularly training could be improved.

To help people now working from home, 3CX says it will be "offering the Standard edition of its software to all organisations completely free of charge for 3 years".

Image source: Zoho
Image source: Zoho

Zoho Meeting

Indian software giant Zoho provides software for many SME business needs, and audio/video meetings are no different. Zoho Meeting allows users to hold online meetings with real-time audio, video, meeting recording and screen sharing, in-session chat and moderator controls. It offers integrations with Zoho CRM, Projects, Calendar and other tools. All transmissions take place through SSL/128-bit AES encryption protocols.

There is a 14-day free trial, after which Meeting costs £6.30 per host per month, which accommodates up to 100 participants and includes storage for 10 recordings. There's also a limited free plan for up to three participants.

Zoho's Small Business Emergency Subscription Assistance Programme (ESAP) offers 20,000 qualified paying customers with 25 employees or less to use every application currently in use for free for up to three months.

Google Hangouts Meet
Image source: Google

Google Hangouts Meet

Google Hangouts Meet is a web-based video conferencing service and is fully integrated with G Suite. Users can join Hangouts Meet meetings using third-party systems, such as Skype, or meeting systems based on SIP and H.323 standards.

The system supports up to 100 users on the Basic G-Suite tier (£4.14 per user per month) and 250 on the Enterprise tier (£20). There are three paid tiers.

Customers can trial the platform for free for 14 days.

Delta users liked the price and ease of integration/use of Google's Hangouts products, highlighting its in-browser functionality. However, some worried about Google's business model and how it might affect confidentiality.

In response to the pandemic, Google has extended its Hangouts Meet offering to schools using G-Suite for Education, including "the ability to record meetings, livestream up to 100k people and add 250 people to a Hangout".

Jitsi

Jitsi-Meet

Jitsi-Meet is a free, fully encrypted open-source video conferencing tool. There are apps for Apple, F-Droid and Android whereas desktop users create and join meetings via a WebRTC-compatible browser (Chromium-based preferred). Alternatively, Jitsi can be installed on a server for self-hosting.

Registration is not required and passwords and pins are optional. Users can set up a video meeting immediately simply by sharing a link.

Meetings can be recorded and livestreamed, YouTube videos can be shared and the usual screen and file sharing features are supported. Jitsi integrates with Slack and there that APIs to allow video to be added to other third-party applications.

Slack

Slack is best known for its text-based chat but paying users can also make video calls with up to 15 people. Prices start at £5.25 per user per month. Free users are restricted to one-to-one video calls. Slack also integrates with third-party meeting software, including Zoom, Webex, Skype, Hangouts and Jitsi.

WhatsApp

Facebook's ubiquitous WhatsApp messaging app also offers voice and video conference calling. It's available for all platforms and is free to use, with end-to-end encryption for confidentiality. Communication is over mobile networks or WiFi and may be adequate for small groups. Competitor Viber has doubled its group call participants limit to 20 in the wake of coronavirus. Calls, messages and shared documents are end-to-end encrypted, however there is no video option.

Apple FaceTime

FaceTime allows users to make audio and video calls from iOS and macOS devices. It's free to use, but as a proprietary Apple standard, it will not work on other devices and operating systems. If all your team members are on Apple devices then FaceTime would be an obvious choice for catch-ups, but this restriction rules it out for flexible multi-party meetings where access to Macs and iPhones cannot be guaranteed.

Jami

Jami is a free, open-source, peer-to-peer, cross-platform, SIP-compatible audio and video conferencing service developed and maintained by the Canadian firm Savoir Faire Linux. It offers end-to-end encryption for chat, file sharing, video and voice and there's no limit on the number or duration of calls.

It's available for all main desktop and mobile platforms, although features differ across each Overall, this is a bleeding-edge tool that's probably only viable for small technically savvy teams at this stage.

Late additions

8x8

Cloud collaboration vendor 8x8 got in touch to tell us they are extending the free version of 8x8 Video Meetings.

The free version now offers unlimited usage, international dial-in numbers in more than 55 countries including local and toll-free options and a browser-based interface that allows users to start or join meetings using Chrome, Firefox or any other WebRTC enabled browser. Meetings can be recorded and there are plugins for O365 and Google calendar apps.

What have we missed? Do you have other suggestions for services that can help staff work reliably from home? Let us know in the Comments.

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