Surprised they didn't already have a service?
Clueless & Witless do / used to have a service which did inter-carrier routing of SMS and MMS messages over their GRX network. It also used to have a hideously mangled old version of BIND that did the number routing too.
Maybe the Energis idiots have managed to screw that up like everything else they have been allowed to touch. (You know you are special when you make C&W look competent).