I am using Flexisip and Linphone with TLS authentication and reg_expires=60 (instead of push). SIP messages sent form A to B are stored on the server only if:
Linphone app of B is closed (UNREGISTRATION)
or
Mobile was switched off (which results in proper UNREGISTRATION)
But if B loose the network for more than 60s (having mobile on and Linphone up), then A cannot send any message to B.
Is there any way to configure Flexisip (or Linphone), so that it could Store SIP messages in all cases, even when B loose his network (=REGISTER is not sent on time) ?