UDP Nat no internal calls

We have a serious problem with Fusionpbx:
If extension is registered with TCP,outgoing calls and incoming calls works.
But if we use udp we can not make or receive calls between internal extension of the same domaine.
We have IP phone that does not support or have TCP option , and we need to make /receive calls with udp .
Please can anyone provide us a real solution to the problem of udp nat.
What kind of IP phone are we talking about here? Have you attempted to isolate the problem to the extension or the phone by registering your problem extension to a different IP phone? If the problem follows you using different phones & different extension numbers then you probably have a network problem.

A log snippet would be invaluable here.
Last edited:
Thank you for your response.
OK let me explain to you:
IP phones are mitel5224.
But look a this:
IPhones mitel or softphone (zoiper,xlite,eybeem) with udp not working.
Same iphones or softphone with another extension with udp not working.
Same extension with softphones with TCP working fine.
We have tested the problem on diffrent location and different network.
Please note that fusionpbx is on public IP with no nat.
Iphones or softphone (lan) =>internet=>fusionpbx(public IP)
Please note that with udp phones are registered and can make outbound calls but the can not receive calls or call each others.
When you call an extension registered with udp , there is no ringing, after a while you are transfered to voicemail.
On fs_cli you see (user no answer).
With TCP there is no problem.
2019-01-18 11:24:19.601871 [DEBUG] sofia_glue.c:1264 sip:100@MY_PUBLIC_IP:37278;rinstance=c538616cc021e3e4;transport=udp Setting proxy route to sofia/internal/100@MY_LOCAL_IP:37278
2019-01-18 11:24:19.601871 [DEBUG] sofia_glue.c:1295 sofia/internal/100@MY_LOCAL_IP:37278 sending invite version: 1.6.20 64bit
Local SDP:
o=FreeSWITCH 1547792035 1547792036 IN IP4 FUSIONPBX_IP
t=0 0
m=audio 18624 RTP/AVP 9 102 103 0 8 101 13 104 105 106 107
a=rtpmap:9 G722/8000
a=rtpmap:102 G7221/32000
a=fmtp:102 bitrate=48000
a=rtpmap:103 G7221/16000
a=fmtp:103 bitrate=32000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=rtpmap:104 telephone-event/32000
a=fmtp:104 0-16
a=rtpmap:106 telephone-event/16000
a=fmtp:106 0-16
a=rtpmap:13 CN/8000
a=rtpmap:105 CN/32000
a=rtpmap:107 CN/16000


Staff member
I don't believe this is an issue that is in any way related to the PBX, it is not suitable for debugging on the forums, well, not by me, I'm not prepared to spend ages back and forth in the forums on an issue that I can probably fix in less than half an hour hands on but equally when the solution does not benefit the rest of the community. This problem is highly specific to your particular set up.