Hi all,

We recently installed a DrayTek Router at 2 x Sites and created a Site-to-Site VPN using IKE with AH.

There is a Telephone System at Site A and IP handsets using SIP at Site B. Site A can make calls to site B using the VPN to other IP Phones. When they try and make a call from an IP Phone to a TDM Digital Terminal they can hear the other person on the TDM but the person on the TDM can hear nothing. Any idea if this is a problem with the Drayteks?

I have asked one of our distributors and they had a problem using the 2830's blocknig certain SIP ports as well. The problem was fixed when they relpaced them.

Is this a known problem? Is there a Fix?



Dave

I have replaced both sites with 2 x DrayTek 2820 Routers.

The VoIP over the VPN is now fine.

I believe this to be a problem with the DrayTek 2830's Firmware. I am waiting for an answer from their Tech Support.



Dave

DrayTek tech support suggested the following:

"> Does the PBX just have one IP? Because there is a security mechanism
> relating to fake ARP addresses that is enabled by default on the Vigor
> 2830 but disabled by default on the Vigor 2820.

>> ip arp accept ?
> Ethernet source address doesn't match ARP sender address.
> Accept illegal ARP REPLY packets or not.
> %% ip arp accept <1/0>

> %% ip arp accept status

>> ip arp accept 1
> Accept illegal ARP REPLY packets."


I have not tried this as it would be time consuming to replace the routers again. I may test it from another connection though.