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The Online Amateur Radio Community host a PBX to allow members to contact each other and hold SIP nets (also known as Conferences)

To request an extension join #sip-network on the Discord server and check the links at the top. Once you've filled in the form someone should be in touch in a day or two to give you the login details.


  • Free calls between extensions on the system
  • Conference bridges
  • Voicemail
  • Listen to the OARC Bridge
  • Searchable directory on supported handsets (Check the docs for your model)
  • More to come

Technical Highlights

  • Support for OPUS, a good quality, low bandwidth codec with Forward Error Correction - Useful for mobile clients or clients connecting via WiFi
  • Support for “HD” audio (G722)
  • TCP support - useful for working around shonky phone / router behaviour and extending battery life on mobile devices
  • TLS and SRTP support to encrypt communications subject to the following caveats:
    • There's no guarantee the person you're calling is using encryption
    • SRTP needs enabling manually, ask in #sip-network
    • Encryption isn't end-to-end

External Access

We currently allow external users to dial specific extensions or into the 1300 net.

  • PSTN - You can dial into the PBX from a landline or mobile by dialling 03331126272 - This should cost the same as a call to a “local” 01 or 02 number and be included in any minutes bundles, but check if you're unsure.
  • Hamshack Hotline - Dial 24107 from any extension.

Outbound Trunks

We're more than happy to setup trunks to other systems. You can dial them by adding a prefix to the extension number.

  • Hamshack Hotline (Prefix the Hamshack extension number with 9)

Feature Codes and special extensions

  • *43 - Echo Test
  • *43 - Reverse Echo Test( Immediately rejects your call, calls you back, and drops you into the echo test )
  • 1002 - Listen to the OARC Digital Bridge
  • *1300/#1300 - Enable / Disable a reminder call for the 1300 Net (Weekdays at 1300)

SIP Endpoint Configuration and Usage

Cisco PhonesCisco Phones Instructions on setting up compatible Cisco IP Phones Cisco 79XX and other 4 digit models The Cisco 79XX (7940, 7960, etc) are primarily designed to be used with Ciscos proprietary SCCP protocol. Many can be converted to use SIP, but the process is painful, and the end result is severely limited and may not work at all.
Grandstream PhonesGrandstream Phones Instructions on setting up compatible Grandstream IP Phones Grandstream 21xx series The 21xx series are still in production, with regular firmware updates. If these instruction don't work for you then please check your firmware version, by pressing the phone's up-arrow key. The example screenshots are from a GXP2140, but should be the same on any Grandstream 21xx phone. }
Mitel PhonesMitel Phones Instructions on setting up compatible Mitel IP Phones Note: Mitel phones can be a bit tricky about working with SIP, and you may need a TFTP server to update the firmware. Some models aren't supported. YMMV Mitel 53XX The Mitel 53XX handsets are pretty utilitarian (ugly) but you might be able to get one for free out of a skip or office clearout.
Polycom PhonesPolycom Phones Instructions on setting up compatible Polycom IP Phones Polycom VVX 450 The VVX 450 is one of the current offerings from Polycom, featuring a colour screen, 12 line keys and support for low bandwidth and high quality codecs such as G722 and Opus. They can be purchased as cheaply as £30 on EBay if you get lucky at auction time.
Yealink PhonesYealink Phones Instructions on setting up compatible Yealink IP Phones Yealink T4XG The Yealink T4XG series is no longer in production but it still a functional and fairly up to date phone that can be picked up cheaply on EBay. They're highly flexible, configurable but lack support for modern codecs such as Opus.

SIP Software

  • MizuDroid - Android / iOS / Windows / Browser
  • Zoiper - Android / iOS / Windows / Mac / Linux

Android F-Droid store

  • baresip - Android
  • Linphone - Android
  • Lumicall - Android
  • Sipdroid - Android
  • SIP Caller - Android

To Do List

We maintain a To Do list of PBX things that need working on Here

oarc_pbx.txt · Last modified: 2022/09/03 20:33 by 2m0iig