My settings are LTE/WCDMA/GSM selected. Other options are WCDMA/GSM or GSM Only.couzin wrote: ↑Thu Jul 12, 2018 4:02 pm Occasionally it happens because of reception. There are issues with some earlier Android devices like S4, 5, 7 that are this: the phone is supposed to switch from 4g to 3g, even down to 2g when signal for the faster data transfers is blocked or weak. Same issue for going from GSM back up to the higher data transfers. Android gets confused, stays on 4g or GSM and drops the incoming call into voicemail because it thinks the phone is out of range or off. Supposedly, if you frequent an area where LTE does not work well but GSM is fine, in Android settings under networks you can select either system to prevent the stumbled switching.
BTW, I'm pretty much home bound lately, and my phone nearly always shows full bars.