1. Did mms work before you did root and Rom flash. If yes, try the suggestion of going back to stock or other that works and getting the Telephony.apk. (BTW good job with that, i'm impressed, I'll let you handle some of my calls with that kind of brain, lol.)
2. If it didnt work before hand, then most likely it is something on the provisioning on the network end, this is rare, but it happens, if this is the case, then you will have to call tech support and pray you have someone with a brain.