Unifi Talk : Gamma SIP Trunks

Unifi recently (and finally) brought Unifi Talk to UK shores, having an ISDN2 PBX that is almost 2 decades old it seemed like the perfect opportunity to upgrade.

One small snag, Unifi isn’t currently supporting number porting to their Talk service for the UK.

Our current provided offers a SIP Trunk service supported by Gamma – so Unifi Talk is just SIP how hard can it be…

Talk is essentially Freeswitch behind a UI and Unifi goodness, so its a reasonably well documented and understood system, and can support practically any SIP provider you’d care to imagine.

Talk configures two scopes internal and external.

Internal listens on port 5060, and External can listen on a registered port or when Static Signaling is enabled port 6767

Gamma has a couple of interesting requirements:

  • Uses Static IP as “Auth”
  • Uses Fixed Port 5060 signaling.

This presents the first problem, we can’t simply port forward 5060 from the internet to 5060 internally as Talk will treat that SIP traffic as internal and the ACL will block it.

We instead need to move the traffic with a firewall rule, taking external traffic on 5060 and forward it to 6767 (the static signaling port) with that completed we also need to allow Internet In traffic for that local forward.


Step 1) Setup Port Forwarding Rules from Gamma Provided IP ranges

    Step 2) Configure FW Rules

    Step 3) Enable Static Signalling

    Gamma doesn’t support registration, or allow inbound ports to be easily change we therefore need a fixed port to forward. Handily Static Signaling exists.

    Step 4) Configure Unifi Talk SIP Provider

    Step 5) Test

    That should be all that is required, if you have one way audio confirm port forwarding and Internet Local rules are properly configured.

    The Zen Diaries Of Garry Shandling

    When Garry Shandling passed away in 2016, he was widely remembered as a top stand-up comic and the star of two of the most innovative sitcoms in TV history. But to those who knew him, the “real” Garry Shandling was a far more complex person. Now, Judd Apatow has created a remarkable portrait of this iconic comedian in the four-and-a-half-hour documentary The Zen Diaries of Garry Shandling.

    Sky Atlantic: The Zen Diaries Of Garry Shandling

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    This is still one of my favourite mad engineering stories on the web. How to fix a 230kV oil filled electricity cable with Liquid Nitrogen.

    It turns out they have a problem with an underground wire. Not just any wire but a 230 KV, many-hundred-amp, 10 mile long coax cable. It shorted out. (Lotta watts!) It feeds (fed) power from the Scattergood Steam Plant in El Segundo to a distribution center near Bundy and S.M. Blvd.

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    That’s where the LN-2 comes in. An elegant solution if you ask me. They dig holes on both sides (20-30 feet each way) of the fault, wrap the pipe with giant (asbestos-looking) blankets filled with all kind of tubes and wires, feed LN-2 through the tubes, and *freeze* the oil. Viola! Programmable plugs! The faulty section is drained, sliced, the bad stuff removed, replaced, welded back together, topped off, and the plugs are thawed. I was amazed.

    Source: engineering pornography