BCM customize Forms

[Jimbo]

Trying to customize "Accounts and Business Contact". Like to add "Group name
- Other contacts" and format the "Field" and "Data type" section so I can
enter Phone Numbers/ext. in the correct format.

I have tried but each time I choose "Data Type" as 'number' and not sure
what FORMAT to use under "Data Type". Or if i am going about this the
correct way.

Any advise would be helpful.

Jim