The present invention is a system and method of providing a GR303 interface to a digital central office. A virtual line group is installed within a line frame holding a plurality of line groups for communicating with analog subscriber telephones. The digital central office utilizes internal proprietary signals to operate the line groups and route calls to a public switched telecommunications network. The virtual line group emulates a line group within the digital central office and provides an GR303 interface for communicating with remote digital loop carriers. The virtual line group provides the GR303 interface without modifying or adding software or hardware to the digital central office.