Transfer of Numbers
When a company first transfers to ISDN they have a number of choices regarding their old analogue telephone numbers.
1. In most cases one or more of the old analogue numbers are transferred across to your new ISDN channels.
2. In cases where the above is not possible, such as a move of premises to another STD area or occasionally, BT (or other carrier) may have technical issues on your section of the exchange, that prevents them being able to transfer your numbers. In those instances there are still a number of choices. A) An interception can catch callers to the old numbers with a "This number has changed to" message. B) An automatic divert (not recommended, as it doesn't give you the chance to educate your callers with the new number(s). C) Make sure you order an ISDN system that also has an analogue line capacity, and keep the old numbers live.