group core : unified prefix
unified-prefix = <prefix-list>
String to unify received phone numbers, for SMSC routing and to
ensure that SMS centers can handle them properly.
This is applied to 'sender' number when receiving SMS messages from
SMS Center and for 'receiver' number when receiving messages from
SMSbox (either sendsms message or reply to original message).
Format is so that first is the unified prefix, then all prefixes which
are replaced by the unified prefix, separated with comma (','). For
example, for Finland an unified-prefix "00358,0" should do the trick.
If there are several unified prefixes, separate their rules with
semicolon (';'), like "0035850,050;0035840,040".