VoFR explained

Voice over Frame Relay (VoFR) is a protocol to transfer voice over Frame Relay networks.^{[1] [2]} VoFR uses two sub-protocols, FRF.11 and FRF.12. FRF.11 defines the frame format of VoFR, and FRF.12 is used for packet fragmentation and reassembly.

Notes and References

1. http://www.alliancedatacom.com/vofr.asp Voice over Frame Relay
2. https://www.pcmag.com/encyclopedia_term/0,2542,t=VoFR&i=54053,00.asp VoFR Definition