A routing procedure is provided to operate in conjunction with a CCS7 telecommunication network that has been upgraded to accommodate messages having signalling link selection (SLS) field that has been expanded from a length of 5 bits to a length of 8 bits. Messages containing an SLS field with a length of 5 bits that are received at upgraded nodes in such a network are converted to 8 bits so as to take advantage of the increased traffic capacity and improved load sharing characteristics offered by upgraded nodes. The Origination Point Code field, and the Destination Point Code (DPC) field in the routing label of a message, as well as the link identification number of the incoming signalling link carrying the message are used to generate an 8 bit SLS code that maintains message sequencing and is uniformly distributed among available SLS codes. The conversion feature may also be automatically deactivated once the number of data packets received at a node containing 8-bit SLS codes reaches a predetermined threshold.