If you are interested in using a VOIP for a landline, that you get either a dedicated phone like a Cisco IP phone or something like an obihai ATA. Once you get

If you are interested in using a VOIP for a landline, that you get either a dedicated phone like a Cisco IP phone or something like an obihai ATA. Once you get it set up, it will just work. For mobile, you can just add a VOIP number as a separate provider in an Android phone and just select the line as needed. Calls coming in will ring your phone as normal and you can make outbound calls by switching the number in the phone app. No secondary app needed.