This sets how many redundant copies of each Internet FAX Protocol (IFP) packet the gateway transmits during a T.38 high-speed fax relay session, with 0 meaning no redundancy at all. Raising this to 1 or 2 trades extra bandwidth for resilience against packet loss on the IP path, which matters specifically for fax traffic because even a single lost high-speed packet can corrupt or abort an entire fax page, unlike voice which tolerates brief loss. On a DS0 group experiencing fax failures over a lossy WAN, an admin might change this from 0 to 1, roughly doubling fax-relay bandwidth for that group's high-speed data phase in exchange for fewer failed fax transmissions.