Sorry, answered the wrong post.
Re the questions, it is what Verizon specify, I think tey an start session wit specific APN’s if they know what they are i.e. VoLTE is going to be going over IMS (not that we support it). Regardless this is the config that Verizon have specified to us which probably comes from the handset specs and these will automatically be starts and stoping sessions with other APN’s.
Re the Tmobile comment the network can tell the unit what APN to use so here the APN might be irrelevant although I hae seen it where the unit is unable to attach if the wrong APN is set.
Regards
Matt