Path: utzoo!utgpu!utstat!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!netsys!vector!telecom-gateway From: OLE@csli.stanford.edu (Ole J. Jacobsen) Newsgroups: comp.dcom.telecom Subject: Some notes on the UK phone system Message-ID: Date: 18 Mar 89 20:09:50 GMT Sender: news@vector.UUCP Lines: 85 Approved: telecom-request@vector.uucp X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.uucp X-TELECOM-Digest: volume 9, issue 98, message 1 of 6 I used to live in the UK about 5 years ago and here are some notes on phones, wiring etc, based upon memory and recent observations. Apologies for any inaccuracies, but I think most of this is close to being pretty much true. First of all, UK and US phones are basically compatible and you can use either on either system (PTT/BOC regulations notwithstanding). It may be that the pulse make/break ratio and rate is different on paper, but it really does work in practice. I have a couple of British phones on my home PBX (yes, I am a phone fanatic) and they work just fine. The standard UK rotary phone, which was all that was available up until about 1980, has 4 wires going into it: WHITE RED GREEN BLUE The WHITE and RED are connected directly to the outside world and corresponds to the US red/green. The GREEN, in simple terms, powers the bell of the phone. UK phones do not have the "anti-tinkle circuit" found in most US phones, and to solve this problem the bell is wired in such a fashion that if you lift the handset of one phone it disables the bell of the other. This allows dialling without the other phone(s) going tinga-linga-ling. In residences with only one phone (very common), the GREEN is simply connected to the WHITE at the wall socket. The BLUE is, as far as I can tell, only used in PBX applications for a ground-start switch. Needless to say, only two wires run from the customer premises to the CO. The above applies to the "old" system. The more "modern" UK phone system, uses a modular plug (different from its US counterpart), electronic phones, and more and more Touch-Tone (in which case the anti-tinkle circuit is unecessary). It is interesting to note how the new British Telecom regulates what you can and cannot do to their system. All phones have to be "BT Approved" which is not that different from FCC sub 68 approved when you think about it. The difference lies in what the consumer is allowed to do. You can purchase an "Add-your-own- modular-extension" kit from any BT store, but you cannot buy a tool to "modularize" an existing phone by putting on the little white connector at the end of your line cord. Such tools as well as open-ended cables can be purchased elsewhere, but your aren't strictly supposed to use them. The availability of different phones is pretty good, and in stores you'll see familiar brands such as Panasonic. Once again there is a peculiar difference: UK handset cords are NOT replaceable, at least not by the consumer without special tools. On phones with modular handset cords, the "release clip" is broken off such that you need a screwdriver or similar object of just the right size in order to get the cord loose. Why they did this is completely beyond me. (I have also never seen "extra long handset cords" for sale which makes sense if you can't easily replace them). As mentioned earlier, many COs or "exchanges" as they are known over there, accept touch-tone dialling, and processing seems even faster than in the US. Calling the US from the UK seems alot faster than the other way around. This may have to do with the fact that there are more hierarchies of switches/LD interfaces through which the call has to be processed over here. Also, I was told by someone who supposedly knows, that WITHIN the UK the ringing the caller hears is generated by the CALLERS CO rather (as is the case in the US) than by the CALLEES CO. This is probably because they use CCITT Signalling System #7 or their own variant where no voice path is opened until the call is answered. My most favorite aspect of the Britsih phone system is the PhoneCard. It is a green credit card-sized card which comes in different values (20 units, 100 units, etc.). Put one in the special PhoneCard phones and dial away *anywhere*. There is no minimum charge, and you can talk until the "money" runs out (1 unit = 10p). Of course, if you call international, the units tick down pretty fast (as displayed on the phone), but the system does have advantages over 0+ dialling and other schemes which require surcharges and minimum deposits. The only drawback is that you need to find the magic green PhoneCard phones and keep a supply of cards, but many stores sell the cards and the phones are becoming more and more common. Another reason to travel to the UK! Ole -------