Zoiper with some wifi do not register

+2 votes


Im connecting in an iphone 6s with a vpn. If a try register with cellular data it works fine, but with SOME wifi an error occurs "transport failure,no transports left to try(503). Ive tried changin al transports options but still not working.

With cellular data i ve no problem.


asked Mar 21, 2016 in Mobile (iOS, Android, WP) by Agustin Picabea (160 points)  

3 Answers

–2 votes


Try to disable STUN when you are connecting via WiFi. Also, check if the routing device is blocking the ports used by Zoiper, which are list below, and if it supports SIP-ALG, disable it.

SIP port is 5060
IAX port is 4569 UDP
RTP port is 8000 and above UDP

answered Mar 22, 2016 by Ivan (18,410 points)  

Hi, thanks for the answer!

STUN is disabled!
The problem is when im at public wifis, for example a hotel or something (i cant check router)
Thanks !


Can u help me?

Most probably these networks block the ports used by Zoiper. You may need to check for more details with the administrator for these networks.

–1 vote

Which flavor of VPN?  And with which VPN client?

answered Mar 22, 2016 by who (640 points)  


PPTP vpn between iphone and pbx.

With cellular data no problem, with some wifis yes


+1 vote

I had the same problem, to solve it:

    Go to Accounts -> Network Settings, click on Transports, change from UDP to TCP.

That worked for me.

Now it works over the WiFi and when I turn WiFi off it automatic connects to the 4G network.
answered Jan 12, 2018 by eduvilla (190 points)  

@eduvilla Bloody LEGEND!!! ... legend!

I registered in order to leave a comment and thank you for this information - This was by far the most frustrating thing about ZOiPER, and you just found the cure!

Thank you!

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