Wikipedia:Reference desk/Archives/Miscellaneous/2017 July 9

Welcome to the Wikipedia Miscellaneous Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 9

Landline-powered phone with speaker phone and/or caller display, for use in the UK

Does such an item exist? If so, can someone direct me to such a model.

By "landline-powered", I mean a landline phone that has either no battery or one that charges from the landline, and no external PSU.--Leon (talk) 18:17, 9 July 2017 (UTC)

I have a very old Binatone Speakerphone 3 that I keep on an extension socket to ring up the electricity company when there are power cuts (mobile coverage completely unreliable where I live). It has no caller display but I can't see why a caller display would exceed the limit for drawing current. Everything like this I see for sale now seems to have a PSU or batteries. However, this might be solely to keep the memories programmed if the landline goes down. Thincat (talk) 19:23, 9 July 2017 (UTC)

• So far as it applies, old-style landline phones in the US run off their own electric supply, separate from the electric utility. So if you have an old-style phone (1990's or earlier, such as the Princess Phone) it will work even if the power goes out. Britain is a rather strange appendage of Europe, so it may have different laws of physics applicable. In any case, I visited my parents on June 23 2015, when there was a derecho that blew down about 1/4 of the trees locally. I bought eight five-pound bags of ice to save the meat in the freezer. But two of our older non-modular phones worked, as the phones service never went out. The DSL stank, of course, but that's par for the course. μηδείς (talk) 03:54, 10 July 2017 (UTC)

Just look for a corded speaker phone with caller ID on your favourite shopping site. You'll likely find some do not need mains power or batteries. If they do have a battery or mains power check what features it's needed for. I think most corded phones work without mains power or batteries for power cut situations (even some cordless phones have some sort of emergency mode where you put the phone onto the base station and use it to power the base station enough for a speaker phone mode) although some may need it for the display or speaker phone component, but on others it may only be e.g. for preserving the clock or caller memory or increasing the volume of the speakerphone or perhaps for a backlight. E.g. Amazon.co.uk has this with no sign it had any support for mains power and per comments definitely doesn't require them and this which from reviews clearly supports batteries but doesn't require them.

As Thincat mentioned, it does unfortunately seem that many nowadays do need external power for either the display or speakerphone component or both (well often anything more than a simple phone) I presume due to the limitations relying on the phone line power places and the fact many consumers nowadays don't care. Note in particular power limitations when the phone is not offhook/in use probably mean the display has to be fairly low power. (As one of the reviewers in the second link mentioned also the effect if you have multiple devices connected to the phone line.)

Speaking generally, the modern phone system and modern phones tend to be a lot more tolerant of differences from local specs, I have a phone with optional batteries (think for memory or maybe backlight or both) purchased in Malaysia maybe about 10 years ago that also works in NZ including the caller ID function IIRC (definitely it works with my fibre caller ID which I presume follows the NZ specs) and of course the speaker phone component. I wouldn't be surprised if it also worked in the UK although using it in either NZ or the UK if it's plugging into a phone line provided by the telco would likely violate your network agreement and/or the law. Still import requirements tend to be much more relaxed nowdays, in the UK likely helped by EU law meaning it's easier for importers to import whatever crap comes from China and sell it for legal use in the UK so you can definitely find stuff as shown.

Nil Einne (talk) 05:26, 10 July 2017 (UTC)

This is the Ofcom guidance on what will work during a power cut - [1]. Those with any sort of display do appear to need an additional power source, but some (e.g. BT Decor 2200) have batteries for that purpose. Wymspen (talk) 11:50, 10 July 2017 (UTC)

I seem to recall that old-fashioned phones worked off the small amount of electricity BT sent down the line. I think. --Dweller (talk) Become old fashioned! 11:55, 11 July 2017 (UTC)

Of course they did, and still do. The voltage at the telephone exchange was nominally 50 volts in the BT system, but was normally a volt or two higher. When measured at a subscriber's line jack, it was about 48 volts due to line loss - see British telephone socket#Sockets. Akld guy (talk) 23:53, 11 July 2017 (UTC)