Not registered on network

I had the exact issue, with the same phone. I now have a Samsung A20 too.  TMo technician had me change the mobile network to work better with the tower in my area. The tower is LTE/3G and 4G.  I needed to change my settings on phone to be LTE/3G.  What I had previously was LTE/2G/3G.  My tower is heavily trafficked and needed to be able to communicate better with my phone.

Again….change your mobile network on your settings to agree with your tower, most likely LTE/3G. 

Call a Tmo tech - not a rep - but a technician if you need help doing this. 

FOUND A CURE!  I had this problem over and over and missed calls and texts and had to restart my phone to make it work, plus tried 2 new SIM cards from the t-Mobile store to try to fix it.  I finally got a tech supervisor at T-Mobile who explained that the problem is multiple 5G towers which don't pass connections over well.  He had me switch to LTE/3G/2G which solved the problem.  I don't stream movies on my phone and don't need 5G if it creates this major problem.  Here's what he did:

settings> connections> mobile networks> network mode> select LTE/3G/2G then RESTART Phone.

This seems to work fine so far.

TfromTX wrote:

I had the exact issue, with the same phone. I now have a Samsung A20 too.  TMo technician had me change the mobile network to work better with the tower in my area. The tower is LTE/3G and 4G.  I needed to change my settings on phone to be LTE/3G.  What I had previously was LTE/2G/3G.  My tower is heavily trafficked and needed to be able to communicate better with my phone.

Again….change your mobile network on your settings to agree with your tower, most likely LTE/3G. 

Call a Tmo tech - not a rep - but a technician if you need help doing this. 

I had the same issue on my son's Samsung Galaxy A32, and changing the network to LTE/3G worked. It's unfortunate that I'm paying for 5G and we can't use it.

Did you put your SIM card in it?  Is your SIM inserted the correct way?  Is your SIM activated?

This is also happening to me, and, I also randomly receive the "server unreachable" error.  I have brought it back to TMobile several times and they have replaced the SIM card...STILL...nobody knows how to fix this.  I had a ZTE that worked perfectly...this Samsung is a piece of garbage...

I live a half block from a 5G transmitter, but have only a 4G phone. However, I think having a powerful site so close may be part of the problem. Maybe it gets overwhelmed by the 5G signal and doesn't find other sites. Goodness knows, in Santa Monica we're well covered by all sorts of networks.

odds are because that tower is so close even if its having some issues its probably still showing as the strongest signal and keeping you there instead of kicking you to the next closest tower.

only guessing here..if its a 4G only phone then the 5G side should have zero affect on you since most others would be connecting to the 5G side and not the 4G side..

was your phone purchased from TMO or brought in from elsewhere?

is there zero 5G there or is your sons phone the only one not picking this up? and is this a new phone? which phone did he switch from? and did you use the same sim card from the old phone and put it into the new one or did they give you a new sim card?