IP phone dial tone

[stevomorrison]

I have an BCM 400 4.0 with IP phones connected. I have 2 phones located off site connected via a dedicated 10mb link between sites. These 2 phones are having issues with recieving dial tone most times. They can still dial out and recieve calls but the dial tone doesn't seem to be there most of the time. Just dead air. Any ideas.

 

[phrk]

Stevo,

I had this same problem too very recently and was able to resolve it. In my case the switch was a BCM50 3.0 and an offsite 1120E phone.

Sometimes the remote set has DT, sometimes not..reseting the phone does not help..right?

I tried latest patches - no luck.

The main site used a Contivity 1010 to establish the vpn tunnel to the remote site. Within that device was a setting for "NAT hairpinning". I just checked the box for that and the problem disappeared.

It was quite easy after troubleshooting it for days.

I wonder if you have a similar configuration? If so, definitely try that check box.

I snagged this process off the Nortel site:

To configure hairpining:
1 Select Services > Firewall/NAT.
2 Click Edit beside Contivity Firewall.
3 In the NAT Hairpinning section of the Firewall/NAT > Edit page, check the
hairpinning box.
4 Click OK.

Looks kinda similar to the 1010 I was using.

I hope this applies to you because having that problem is a real pain (as you know).

extra information:

Before I found the hairpinning, I found clearing the NAT Flow cache on the 1010 seemed to temporarily correct the issue when the remote site's ISP changed the DHCP address. I also saw an unexpected IP address for the IP phone in both the BCM monitor and the IP phone resources page. BCM monitor would show correct IP address when phone worked OK. It showed the IP of the next hop router at the main site when the issue existed. Basically the BCM was always able to register the phone (TCP port 7000) but the RTP UDP ports that are dynamically established were routed to outer space.