Aspects of the present disclosure include systems, methods, and devices for routing communications that ingress into a telecommunications network by appending a virtualized trunk group identifier or other customer identifying number within a Session Initiation Protocol (SIP) messages associated with the communications. In one particular embodiment, a user field within header information of SIP messages may be appended with a trunk group identifier unique to a particular customer device providing the communication to the network. Specifically, a customer premise device (such as an integrated access device (IAD)) may be configured to append a customer-specific trunk group identifier number into a portion of a header of a SIP message of the communication. The call and associated SIP message information, including the appended trunk group ID, may then be routed to a host routing device.