LG G5 (LS992) Will It Move Over From Sprint To T-Mobile As Part And Work After 3G Retirement

Oops..  I read the chart wrong on B66 and B71 (they are not supported by LG G5 - not that T-Mobile may not support them). 

Just correcting myself on that part of my question. 

It does not change my original question though, and would appreciate any help you may be able to give me.  Thank you.

Thank you so much @syaoran .

It is true that I have seen some phones list VoLTE for only AT&T and T-Mobile (such as this phone ), it seemed to have more to do with them only supporting the GSM/UMTS network, with no support for CDMA networks.

As far as standards are concerned, VoLTE (not HD-Voice, or Extended Range LTE over band 13) has a standard (which although not all options are required, should work between carriers that implement it and allow it): 

• https://www.gsma.com/futurenetworks/wp-content/uploads/2014/05/FCM.01-v1.1.pdf

Even Sprint acknowledges that VoLTE on the their network should transfer over to T-Mobile (for capable devices, which in the “Which Devices Support VoLTE” section, it lists LG G Series): 

• https://www.sprint.com/en/shop/services/volte.html#:~:text=I%20am%20now%20using%20a,you%20are%20automatically%20using%20VoLTE.

However, I do notice in the last link above, in the “Which Devices Support VoLTE” that it does say LG G7 and newer.  The G5 LS992 has a “Voice clarity” option which some suggested was how to turn on VoLTE (although I found another forum that stated they had an actual VoLTE setting - which my phone does not have).  I went ahead and looked up the original specs for the LG G5, and I found that the LS992, and the factory unlocked RS988 versions of the G5 do not specifically list VoLTE in the specifications section, although the H831 version does list it in it’s specification section.  Interestingly enough though the H830 version of the G5, T-Mobile’s version, does not list VoLTE (even though their is a T-Mobile support document that lists it as having VoLTE). 

So, after your post got me to digging a little further, it seems like the Sprint LG G5 LS992 out of the box may not actually have VoLTE like I thought it did (at least that helps sooth my heart in not feeling frustrated in having to buy another phone when I thought my phone had the appropriate capabilities out of the box).  Although, if you have a link that shows that Sprint’s VoLTE and T-Mobile’s VoLTE are not compatible, that would be helpful too.

Thank you so much for taking the time to answer - I really appreciate it.

I have a Sprint LG G8 that I was using on a Sprint MNVO and I just found out that the MNVO is switching to Tmobile and I had to get a new phone .

I think your question was answered since Sprint LG G5 version does not have VOLTE setting, but this is my experience which hopefully might help someone with a similar situation: I have an LG G5 that's always been on TMobile network. In September I got a text from TMobile suggesting to activate the VOLTE setting, which I did. That indicates that TMobile provisioned functionality for my LG G5. Also, the IMEI checker said it was approved for activation in September 2021, so it is apparently on the whitelist during the mandatory VOLTE rollout. That same week a store attendant contradicted information on the website and insisted that I need to replace the phone "because LG stopped making phones in 2021". However, I  think that was a lie because TMobile normally sends a text message directly to the phone when it needs to be replaced, which I did not receive and in November 2021, TMobile website still has an LG G5 support page.