Carrier SIP trunk to AltiGen IP PBX

[Anonymous]

I have an Adtran total access 908e with a carrier PRI connected. From there I route calls to and from an Altigen IP PBX over a SIP trunk.

The carrier is eliminating the PRI and wants to deliver voice over a carrier SIP trunk. I could bypass the Adtran and go SIP directly to the PBX but i'd lose my analog ports which are still needed.

Can someone tell me if the 908e can have two SIP trunks like this and how to go about adjusting my config for this?

Any help would be greatly appreciated.

[jayh]

Yes, it absolutely can have multiple SIP trunks. You'll probably need to get the SBC license for media anchoring if the PBX is behind NAT. We do this all the time and it works without a hitch.

One other gotcha, most of the configuration guides show all of the voice grouped-trunks with an accept-all  "$" pattern. On the trunk going to the PBX, you'll want to limit this pattern to just the DIDs that the PBX is programmed to accept. This will allow calls from the analog phones to route appropriately.

[Anonymous]

Thanks Jayh. I'm pretty sure we'll need that SBC license. Is there a guide out there for AT&T IP Flexible Reach SIP trunk configuration? I cannot seem to find one on Adtran's site and the one AT&T sent is for a Netvanta.

[jayh · Accepted solution]

Netvanta and Total Access 900 should be very similar. You should be able to use the Netvanta guide pretty much directly. If there's syntax you don't understand, let us know. Depending on the specific Netvanta model there may be some slight differences.

I think (hope) that things have changed recently but it used to be the case that getting the SBC license was a royal pain where pills don't reach, so if you need it don't wait too long. We're talking weeks, dealing with distributors, including snail-mail delivery, to get a license key.

I haven't been involved in the license purchase process recently but I'm pretty sure it's fixed now where you can get it instantly online.

[ngefvert]

What exactly are you using the analog ports for?  I ask because if you are using them for something like a fax machine or modem, you may have issues using that hardware once the traffic is going over the SIP trunk...

[Anonymous]

There is a fax machine. Is that a limitation of the Adtran Total Access or ATT IP Flex? Other than that there's a couple analog phones and an overhead bell.

[jayh]

Fax over unconditioned VoIP can be problematic, but is actually very doable if you're diligent. Many of the tweaks done to make VoIP sound good such as packet loss concealment, echo suppression, AVC, G.729 codec, and the like wreak havoc on fax so the configuration needs to be optimized for fax transmission.

The Adtran Total Access is very powerful when it comes to optimizing fax and should have no issues if properly configured. Make sure that the AT&T Flex circuit is also optimized for fax, specifically that it supports T.38. If both the SIP trunk from AT&T and the Adtran are configured properly there should be no problems. We have hundreds of fax lines in service behind Adtran Total Access 900 series devices with no issues.

In discussions with AT&T, ensure that they support fax transmission and T.38, configure the Adtran properly, and you won't have any problems.

[Anonymous]

Been meaning to reply Jayh. The Netvanta guide worked but the SBC licensing was key. Took a few days to get from distribution but it made all the difference.

Curious...from what I've read the SBC licensing is needed so the Adtran can act as a gate between ATT's public network and the IP PBX on the local network. If the ATT router was on the LAN would we still need the SBC licensing on the Adtran?

[jayh]

The primary thing that the SBC license does in this case is allow media anchoring. It modifies SIP packets traversing from one SIP peer to another to use the IP of the Adtran interface facing the peer as the media endpoint. This fixes routing in many cases where the RTP would be sent out the wrong gateway and not reach the other SIP endpoint.

Interestingly, in much earlier firmware SIP-to-SIP through the device just worked without the need to buy the license.