If your provider requires to dial 1+areacode+7digits and you need to simplify dialing for the users then create three rules.
For example:
Area code is 3 digits and your area code is 211
so, three rules will help you to simplify dialing:
First rule:
length of dialed number is 7 digits
Strip 0, prepend 1211
Second rule:
length of dialed number is 10 digits
strip 0, prepend 1
Third rule:
Prefix 1
length of dialed number 11
strip 0, prepend nothing
User will be able to reach 7 digits local number, other areas without need to add 1, and can dial full number required by the provider.
So if you need to reach local number 1234567
Then you can dial
1234567
2111234567
12111234567
PBX will always dial 12111234567 as required by the provider's line.
Another solution is to use e164 processing rules.
It is slightly more complicated, but it will care about dialing plan required by your lines.