prefixing call before routing to ss7
the following applies to calls from sip->ss7
ie. ss7<-------NSG<-------PBX
effective_caller_id_number=<prefix here>${caller_id_number}"/>
this will apprend digits to number
the following applies to calls from sip->ss7
ie. ss7<-------NSG<-------PBX
effective_caller_id_number=<prefix here>${caller_id_number}"/>
this will apprend digits to number