toast4867
MySudo needs google play services installed if you'd like notifications to work. also you need a secondary 'stock' device (android or iphone) in order to purchase your mysudo subscription and then you essentially 'copy' the account over to your graphene device. you need to maintain the second device in order to continue your subscription payments afaik.
jmp.chat works pretty well but I think some ppl have experienced issues with it behind vpn intermittently. I'll be honest, I've tried a couple of options but I largely stick to using mysudo and google voice on my iphone and just use the sim card number on my graphene pixel. I haven't been able able to get to a comfort level that the voip apps will always notify me of calls/sms reliably on my graphene device with always running vpn. Any my business and personal calls are too important for me to take that chance...