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IP Phone in Home Working scenario doesn't register

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svallespin

Technical User
Nov 13, 2008
7
ES
Hi guys!
I need to install a DBC422 01/01001 (R3E/R4H/R4B) at employee's home because of the famous H1N1 virus.
He has a cable modem at home and the idea is connect the phone to it.
If I connect the phone directly to the cable modem, it works fine. The phone is configured with DCHP and the public IP of the gatekeeper. We don´t use Software Server. The cable modem gives a public IP to the phone (IP that assigns the ISP), then phone register at gatekeeper and calls work OK.
BUT when I connect the phone to the router, the desired option, it can't register at the Gatekeeper. (cable modem <-> Router <-> IP Phone and a PC conected to router, not in built in phone switch)
The router gives a private IP to the phone (192.168.1.xx), and that private IP is configured in router as DMZ (demilitarized zone) and all the needed ports are open to that private IP (exactly, I opened 0 to 65000 to avoid problems).
I used wireshark to look for the Ethernet packets at both sides. When phone wants to register, it sends a RAS (registrationRequest) using H.225.0 protocol to the gatekeeper, then gatekeeper sends back a registrationInProgress packet and a registrationConfirm to the phone, and here is the problem. Gatekeeper doesn't send that packets to the public IP of the cable modem, it uses the phone's private IP!!!, and ofcourse, packets never arrives to phone. The phone "answer" is two more registrationRequest. In the debug log of phone it appears TotalTimeout RRQ or RRQPER and LOGON REJECT msg rec, Reason=1 Data=3.
I look inside the registrationRequest packet that phone sends, and in the H.225.0 RAS field, TransportAddress for callSignal (port 1720) and rasAdrress (port 1719) are 192.168.1.xx, when it has to be the public IP of cable modem. Bad thing...
Then the question is: Is possible to configure phone in a way that makes the H.225.0 RAS packet with the public IP?
Any suggestion?

Thanks for your reading.

MD110 VERSION=CXP1010116/4/TSWSP03/R4A
ELU32 R6A/R5A
 
I don't think this is possible with your current configuration, MX-one does not support NATing.

TELEC3
 
Hi,

TeleLion is right.
You can use a router that sets up a VPN tunnel towards the office, avoiding the NATting issue...


/Daddy

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!
 
H.323 is not good with NAT anyway and can be a real pain to setup. SIP is better but you don't have this options. So a VPN connection would be best but obviously you need the hardware/firewall at both ends to support this. Possibly a firewall to firewall IPSEC connection would be the best.


Lee Mason
Optimal Projects Ltd
 
Bad news...
At office we have a firewall that supports VPN's but the router at home doesn't. If we have to purchase a firewall for the employee... I think the most economical solution could be to request another cable modem for a few months to our cable company. One for the PC and the other one for the phone.
Thanks a lot guys!!!
 
VPN boxes costs around €250. not too expensive in my mind (plus you can reuse it?)

/Daddy

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!
 
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