This read-write integer, ranging from 1 to 65535, determines the delay in milliseconds that the equipment allows for reception of a backward MFC signal before treating it as failed. An admin tunes it to accommodate the round-trip signaling delay of the specific interconnection, since MFC compelled signaling requires a backward-direction acknowledgment before the forward register proceeds. For example, leaving this at its default of 15000 allows up to 15 seconds for a backward signal to arrive before the call setup times out.