Remote interrogation
Answering machine facility that allows messages to be retrieved from another phone.

REN
Ringer Equivalence Number. Printed on all BT-approved fixed phones and peripherals. The sum of the RENsof all devices connected to a normal wired phone line should not exceed four.

Repertory Dialling
Sometimes known as "memory dialing" or "speed-calling." A feature that allows you to recall from 1-to-99 (or more) phone numbers from a phone's memory with the touch of just one, two or three buttons.

Roaming
Using your cellphone on networks other than the one to which you pay your monthly line rental. In other words, using your phone abroad. Roaming is available on all of the UK digital networks. How many countries you can roam to will depend on the number of roaming agreements your network has signed, and on the type of phone you have access to. Roaming must be requested from your network or airtime provider.

RF
Radio frequency. Term used to describe the signal transmitted or received by a mobile phone.

RS232
Connection socket commonly found on computers. Some cellphones have the ability to be connected to a PC through this socket to facilitate the updating of personal directories, or for writing SMS text messages.