We have a site which has just installed SIP trunking to replace the BRI trunks. The system is in the UK.

The BRI trunks detected the local area code so if someone dialled 123456 then it automatically knew it was a local call and the area code prefix wasn't required.

The SIP trunks don't do this. Many of our users are dialling 123456 and the carrier is saying it cannot connect the call.

How can we add a prefix of the area code say 02101 when the first digit dialled after the 9 is not a zero?