VoIP Phones - 3cx

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From AAISP Support Site

No longer works

March 2022 - the 3CX soft phone now only works with the 3CX PBX and is no longer a generic SIP client and so won't work with our SIP servers.

Legacy information

Older versions of 3CX was a software phone for Windows, iPhone and Android. See www.3cx.com/voip/softphone Be aware that this stand alone client 'does not receive any software updates or support' from 3CX.

The 3CX PBX is very different to this soft phone, and does work with our SIP service.

This SIP software on an iPhone just works.

3CX Feature Notes
Tested on FireBrick SIP Server Yes - DOES NOT WORK ANY MORE
IPv6 Support Possibly not
Versions Tested iPhone
NAT Tested Yes, Worked on 3G data services


iPhone 3CX Configuration Settings Example
Name: Your name
Display Name: Your name, etc.
User: Your phone number
ID: Your phone number
Password: ******
Local PBX: voiceless.aa.net.uk
External PBX IP: voiceless.aa.net.uk
PBX Port: 5060
Stun: Empty
Proxy: Empty
Local SIP Port: 5065
First RTP port: 4000
TCP Transport: Off
NAT HElper Off
Echo CAncellation: On
G.711 (aLaw) On
G.711 (uLaw) Off


  • Disable STUN by deleting the stun server settings
  • Disable NAT helper
  • Enable/Disable echo cancellation depending on what works best for you
  • Force a-law audio (probably unnecessary).
  • Also works over 3G (dependant on signal!)
  • Also see Blog post

Firewall & Security

  • Also see the VoIP Security page for information about securing your VoIP service.