Nothing in the logs that stands out to me but it is definitely related to VWMI. If I disable it no reboots. The reboot only occurs when the mwi bit is *not* set (OBI200 <Debug>: +++ mwi notify state 0), no voicemail in the system. Workaround is to not set VWMI but obviously this is not ideal given I won't know if my PBX has a message for this extension. I suppose I could use the phones voicemail but... I guess I'll try that but it is dissatisfying to have a buggy system.
I used
this guide to set up the extension if someone who knows more than me (which is not that much) or thinks of something I should try. I can post logs as well if desired. I would like to resolve this if possible. I am aware it may be an issue with the phone but Gigaset's support is terrible, do yourself a favor and purchase from them.