mumper said:
I got the impression it was similar to MSN Messenger and didn't know it included telephones as well -
No, Skype is an internet based telephone service (voice over IP) although is shares many characteristics with instant messaging and has an instant messaging and file exchange capability built in.
Most of the other voice over IP clients are less friendly in my view and far more phone service focused.
Skype is a peer-to-peer service, it uses the clients around the internet to handle most of the internet communications work (your client will move messages, encrypted and in the background) for other people. You can break out from Skype onto the telephone network (usually close to the call destination so only paying a local call charge) and can also buy your own number so people can call you from a regular telephone number and come through to you on Skype (without them even knowing).
Using a high quality USB phone handset with Skype improves call quality a lot.
Some alternative voice over IP (VoIP) services support the use of special phones that plug into your network (or your internet connection) directly and work for all other purposes just like another phone. You can get devices to connect your existing phones (or your DECT base stations) to the internet as well as the existing phone network and let you choose which network to call out on. This has the advantage of not needing you to connect through a computer. Your computer does not need to be on, just your internet connection.
Many VoIP services use a central infrastructure (rather than Skype's peer-to-peer) approach to connectivity between different parties and also between them and the standard telephone network. This generally costs more than the Skype approach but can provide better quality.
At present, there is no reliable emergency call service available with VoIP services. BT are working on this (they provide a VoIP service now). You do need to have a normal line as a fall back.
There are many alternative call carriers available now many of whom use the same VoIP capabilities (using up all that spare DOT COM capacity) but in the background so bit to your door is still handled by BT (or NTL, Clueless & Witless, etc.) but you only pay for line rental as your calls are carried/charged else where.
For example, we use call18866 and ALL UK calls to standard numbers cost us 2p. Yes. 2p. However long - that is the initial call charge and then it costs 0p per minute. That saves a lot of money.
Stuart