[asterisk-users] string length in dialplan

[Jerry Geis]

I am trying to find out how I can tell the length of a string actually
CALLERID(num) in the dialplan.

How is that done?

If need to test the length of the CALLERID(num) if its less the 10 digits I
need to set it to a known value or insert 0's at the beginning until it 
is 10 digits in length.
My PRI provider needs it set to 10 digits always.

Thanks,

Jerry