FreshPhone VOIP on CellC using Huawei B315s-936 LTE router


Well-Known Member
Oct 7, 2006
I had a B315s-936 setup a while ago for FreshPhone and it worked well. I intended reusing the router, this time to provide Internet and VOIP on a CellC Home Connecta Flexi bundle. I tested the setup thoroughly on my existing CellC data contract SIM, and it worked fine. However, after I had bought a new prepaid sim, converted to the Home Connecta Flexi and loaded a 100GB bundle, the VOIP service no longer works correctly. I can make outgoing calls, but incoming calls end up with a not-available voice message, if voice messaging is tuned on, or engaged signal if voice messaging is turned of on the FreshPhone dashboard.

The only significant difference I can spot is that the contact sim roams on Vodacom (and it shows on the router web interface), whereas the prepaid Home Connecta Flexi is supposed to roam on MTN (as per CellC Home Connecta Flexi web page), but currently shows CellC.

I switched back SIMs twice, and the problem only occurs with the Home Connecta Flexi sim. I also ran tests calling from another FreshPhone number, and get the same results.

Has anyone got an idea what the problem may be? The router setup is exactly per FreshPhone instructions. Would MTN be blocking ports? I can repeat the tests with an MTN sim, but is is a bit of a pain.


Well-Known Member
Mar 9, 2017
Hey @Johnit, I've seen issues like this before, it could be the provider blocking SIP, you may need to log a support ticket with them but I have managed to fix this on other networks like Vuma/Afrihost by enabling SIP ALG and then setting up the outbound proxy on the device to use, its a bit of hit and miss some times, SIP ALG can break the SIP connections on some network and fix it on others. I would suggest checking SIP ALG on the router, if it is not on then try to turn it on and use the proxy, if it is on then try to turn it off and see if you can hold a registration.