This read-write Integer32 (0-255) sets the Type of Service value placed in the IP header of control packets used for VoIP call signaling on the gateway. An admin cares because the TOS/DSCP value determines how upstream routers prioritize the signaling traffic relative to other IP traffic, and a low priority value can cause call setup delays under network congestion. For example, an admin experiencing slow call establishment during peak WAN utilization might raise this value to mark signaling packets for higher-priority queuing.