So everything points to this being feasible, including previous posts. Here's my dilemma:
Running Zoiper Premium with push service on Samsung S9+.
Running Grandstream IP phones in the office and at home.
1.) Can never get two lines to accept inbound calls on Zoiper at the same time. Only the active line even when both are registered. Which ever line is active/default will accept and make calls. The other ignores calls. Even when no other devices are registered to the DID.
2.) I can get multiple SIP accounts to work on the Grandstream at the same time just fine. When I activate a line on the Zoiper, either one or the other rings. Almost never both. Goal is for both devices to ring. One out of 10 tries both ring. Generally it is one or the other with no detected rhyme or reason.
3.) On Vitelity SIP. What are the optimal settings?