BT have many different features that you may have on your lines, to make things simple UK Wholesale will not change any of these unless you find that you have a service on your line that you no longer require.
Call Divert - Divert calls to your mobile or another landline (*21* divert number #)
Call Waiting - Alerts you of a second call waiting to come through
1571 Answer phone - record your own message, remote access your mail box
Caller Display - See the number that is calling you before you answer the call
Call Barring - lets you decide which calls can be made from your phone
Ring Back - If you call a number thats engaged you can press 5 to automatically call back
3 Way Calling - Speak to two people at different locations at the same time in a 3 way conversation
Call Sign - an extra telephone number which rings differently so you can tell which number was called.
Reminder Call - Set a reminder to call you
Display Number - Present your outbound caller ID for any Telephone number that you own