Huawei B315 voice issues

I'm using a Three voice sim in my b315-22, seems to be working ok for data.

However the ability to make calls is temperamental. Sometimes when I call it works, sometimes it's just quiet after dialing. I've got 2-3 bars of 3g. When it does work and I make a call it needs to switch to 3g as voLTE isn't supported by the router or Three. My issue is that it doesn't switch back to 4g after the call, even though the 4g signal is stronger.

Has anyone experienced this? I wonder if the B525 is more reliable?

Thanks

Edited by deleted (Thu 04-Apr-19 02:43:03)