Here's one list of phones known to be either compatible or incompatible with T-Mobile band-12 and VoLTE.
Looking at the specs for the P2, it doesn't look like a very good phone for T-Mobile:
GSM: 850, 900, 1800, 1900 MHz
UMTS: 850, 900, 1900, 2100 MHz
LTE (FDD): Bands 1, 3, 4, 5, 7, 8, 20, 28
LTE (TDD): Bands 38, 40
The highlighted bands are the ones commonly used* by T-Mobile. Missing are UMTS 1700 and LTE bands 2 & 12.
This would not be my first choice for a phone to use with T-Mobile.
*Only in one market (Myrtle Beach, SC) does T-Mobile have band-5.
T-Mobile put a tower in our area running on Band 12 LTE only. I got a cheap unlocked Alcatel Pop 4 Plus dual sim phone on Craigslist for 40 bucks and it works great. I'm trying to get a Kyocera Dura XE (E4710) to work on T-Mobile, but having problems with it.