In telecommunication, a voice frequency primary patch bay (VF) is a patching facility that provides the first appearance of local-user VF circuits in the technical control facility (TCF).

Note: The VF primary patch bay provides patching, monitoring, and testing for all VF circuits. Signals will have various levels and signaling schemes depending on the user terminal equipment.

Source: from Federal Standard 1037C and from MIL-STD-188