1.Seems 10.1.1.50 is an internal IP.so you either need a external IP for the gateway,or use an H.323 NAT router.(expensive and hard to configure)
2.Are you sure the gateway being set to H.323 G.723.1 mode which fit NetMetting.
3.Make sure gateway’s FAST CONNECT function works with NetMeeting
4.Will you use any gatekeeper?