+1 vote


I have installed the free version of Zoiper 3.9.32144 on my Windows 7 PC.  I am connected to a Mitel 3300 PBX.  I can initiate a call and everything works as expected.  When I receive a call I hear it ringing, but when I answer it I can't hear the other party and they can't hear me.

I've tried changing a few settings, but nothing changes.  I've had other softphones on this computer and they all run just fine.  I really like Zoiper though and would like to keep using it.



in Windows by (140 points)

Hello I have exactly the same problem with Windows 10 and Zoiper Biz version.

Did you find a solution ?


1 Answer

0 votes

I believe the issue is related to a misconfiguration for your network or provider, most likely changing the settings for rport and or stun will help.

Please have a look at this tutorial.

Although it is for android and you are on desktop, the steps are nearly identical for the desktop.


by (11.5k points)

Hi Joachim,

Thanks for the reply.  I've spent the last hour changing setting and making test calls and I can't get it to work.

Both X-Lite and Jitsi work fine on this PC (apart from being memory hogs).  They both run default settings and I just needed to add my SIP account details.

My Mitel 3300 PABX is behind a firewall, but there is no NAT.  The firewall only allows UDP transport for SIP.  Do you have any other ideas?


What firewall is this ? If it allows only udp transport for SIP, it sounds like it is trying to be too clever and rewriting the SIP packets :/

Can you do TLS on server port 443 ?

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