When calling another phone from VOiPo (like cellphone), the phonecall doesn't seem to disconnect.
i.e. Call cellphone, hangup the VOiPo call after talking (leaving the cellphone to disconnect itself), the cellphone still thinks the call is connected.

If calling from cellphone and hanging up the VOiPo line, it works fine.

Thus incoming calls work properly, outgoing don't seem to.
I found my cellphone connected to my parents for almost an hour, thinking that once they hung up, my cellphone would as well.
(they have VOiPo managed PAP2, I have BYOD PAP2)