Would you so kind to help me with my problem:
I have Zoiper(3.8) and Iphone 5s(v 9.3.3)
Create a new Zoipher account :
Account name: AC_NAME
User name: 1000
Additional settings / Network settings
Additional settings / Encription settings
Enable ZRTP - NO Enable
SDES negotiation - Enable
Enable plugin XFER, CONF, REC, ENCRYPTION
The connect It's ok - enable WiFi , down 3G.
I have enable net 3G and WiFi.
If WiFi down , 3G enable( switching between wifi networks and 3g ):
Zoiper gives the following messages: “registration failed Certificate validation Failure 503"