check the setup options.
Link for your phone http://docs.blackberry.com/en/smartp...b8100_gprs.pdf
About smart dialing
You can change smart-dialing options to specify a default country code and area code for phone numbers. If you specify a default country
code and area code, when you make calls, you only need to dial a country code and area code when the codes differ from the codes that
you specified in the smart-dialing options.
In the smart-dialing options, you can also specify the main phone number for an organization that you call frequently. If you specify a
phone number for an organization, you can call a contact at the organization quickly by dialing the contact's extension only. Likewise,
when you add a contact from the organization to your address book, you only need to type the contact's extension.
Set the default country code and area code
1. In the phone, press the Menu key.
2. Click Options.
3. Click Smart Dialing.
4. Set the Country Code and Area Code fields.