Hello. In the UK it is not ilegal to record a telephone call as long as it is for your own use. If you intend to pass this onto a third party then you need to have the persons consent.
I have also found a website which sells telephone recording equipment although it looks like it is separate to the telephone. See below for the link and also a quote from the Ofcom website relating to recording telephone calls.
"Can I record telephone conversations on my home phone?
Yes. The relevant law, RIPA, does not prohibit individuals from recording their own communications provided that the recording is for their own use. Recording or monitoring are only prohibited where some of the contents of the communication - which can be a phone conversation or an e-mail - are made available to a third party, ie someone who was neither the caller or sender nor the intended recipient of the original communication. For further information see the Home Office website where RIPA is posted.
Do I have to let people know that I intend to record their telephone conversations with me?
No, provided you are not intending to make the contents of the communication available to a third party. If you are you will need the consent of the person you are recording. "
http://www.telephoner...elephone/overview.htm
Hope this helps.