I don't use Cell C Fixed LTE much. I just did a quick test and
1. I can't use the Dialer app on the tms webpage.
2. I can't call from the Fresh Phone Android app on my phone.
3. I can't call using a 3rd party SIP app.
All of the above works from Telkom LTE, so I'm blaming Cell C
Thank you for the post, we do not however block any traffic for Cell C.
This could also be the way the Cell C router has been configured.
Ok. It seems like Cell C is working now.