Hi all,

I'm looking into setting up a 3510 purely as an IPPBX, not a router. So, the 3510 will sit on our internal network on which we also have a VOIP->GSM gateway (a device which acts as a SIP trunk, but dials using a mobile network). I wanted to connect to this trunk, but when I go into SIP trunk setup I have to specify a WAN interface. So...

Is there any way to specify that this trunk exists on my LAN or do I have to configure the 3510 so it's 'WAN' connection is actually connected to my LAN?

I have the same, IPPBX but not as router, and found that I needed to plug WAN2 and one of the LAN ports into the same network, giving the internal and external interfaces two IP's on the same subnet. Phones connect to the LAN IP.

I've been playing with the same configuration, I eventually went for WAN1 in a DMZ provided by our existing firewall and one of the LAN ports connected to an access port in the Internal Voice VLAN, I also used a static route in order that Internal subnets other than the Voice VLAN could see the LAN IP address (only really used for management of the appliance)

Seems to work fine so far once the SIP trunk provider had made a couple of config changes to accomodate the fact the Public interface of the PBX is behind a stateful inspection NAT firewall. (Static port for inbound calls to the PBX).

it appears this is sorted in the latest (beta?) formware. I now have the option to select 'Lan/VPN' when configuring a SIP trunk.