I guess I'm confused...
Lets say the user is trying to dial the telephone number:
111-111-1111
The SIP provider requires you to dial 621111111111 to make that call?
Or 631111111111, or 651111111111, etc?
Then make an outbound rule that has:
Total digits: 14
Strip first 2 digits
Yes, you'll have to make a rule per "62" or "65" code, but how many codes do you have already?