I've got a Huawei HG659 on a VDSL line, with a fully functioning VoIP with 2Talk.
There is a Huawei USB 3g/4g modem E3372 plugged in, which takes over when the VDSL line is down. That is working fine too.
When the VDSL line goes down, I can make and receive VoIP calls over 3g/4g, but strangely after a few minutes (about 5 to 8?) I can only make calls. Incoming calls then always get the busy signal.
Has anyone managed to get this to work, or where should I start looking for configuration settings?
The SIM card is DATA ONLY.
Many thanks for sharing any insights - I'm lost ...