9608 remote phone not registering

[redswine]

IP500V2 9.0.12, This phone has been working until the IT company swapped out the firewall and forgot to transfer the VPN settings. Now they don't know what they are. Trying to just get it working as a remote extension. IT says they port forwarded the public IP address and opened the appropriate ports, but the phone goes back and forth between Discover to register and for a split second the phone screen starts to come up with the lines across it, and the straight back to Registering. I have enabled remote H323 Remote extension under Lan1 tab and enable remote worker on the user. I'm confident we're missing something on the firewall, but any ideas what it would be. Monitor shows the phone attempting to register:

11:13:49 218395mS RasRx: v=IFace=LAN1, Src=73.172.126.80:49301, Dst=172.16.1.250:1719 peb=0
RasMessage = gatekeeperRequest

11:13:49 218395mS H323Evt: Recv GRQ from 49ac7e50
11:13:49 218396mS H323Evt: e_H225_AliasAddress_dialedDigits alias
11:13:49 218396mS H323Evt: found number <253>
11:13:49 218396mS RasTx: v=Src=172.16.1.250:1719, Dst=73.127.136.88:49301 peb=0
RasMessage = gatekeeperConfirm


Any advice I can give the IT guy? Thanks

 

[icet500]

Do you have default route to the customer firewall/gateway in IPO routes? 0.0.0.0/0.0.0.0/Gateway_IP/(LAN1).

 

[redswine]

Do you have default route to the customer firewall/gateway in IPO routes? 0.0.0.0/0.0.0.0/Gateway_IP/(LAN1).

Yes

 

[icet500]

You will need to double check the ports being forwarded.
1719 UDP
1720 TCP
1300 TCP if TLS is enabled.
RTP/RTCP the range specified by the system's RTP Port Number Range (Remote Extn).

enable "Keep Alive" on LAN1>voip.

Also, what do you have configured in LAN1>Network topology?