I have a SIP connection with "Default" STUN server activated which means stun.zoiper.com. However, using this default I cannot connect to my SIP provider because possibly either the Zoiper Android client or the Zoiper STUN server is wrong.
In this case you can request the needed STUN configuration from your provider and replace the predefined STUN options under your SIP account settings in Zoiper.
Some providers might require that you disable the STUN, in all cases you would need to clarify this with the service provider.
on IPhone 8+ zoiper worked in a shopping mall free wifi, but at home it fails. both my Iphone 5s and Ipad work at home.
so if the 3 devices workin public wifi, then is it not logical to assume that the STUN server and its parameters are ok?
if 2 devices work thru the home wifi and its network , isn't it logical to assume that the ISP, the router, the network are ok?
conclusion is that Zoiper on the iPhone 8+ at home is not compatible with the home network.
with STUN disabled
REGISTRATION FAILED no DNS results (923)
i am clueless
In case you are using the free trial, go to Setting>Advanced and on Global STUN uncheck Use STUN and the error will be cleared.