[Q] PLEASE HELP! Verizon S3 on Tmobile urgent question

Please forgive me if this has been asked already multiple times, but I can't seem to find any recent answers that help.

I currently have Verizon for service and my wife and I each have the Verizon S3 phones.

A few days ago she had gone to the Tmobile website and saw the cheaper rates and ordered 2 sim cards for Tmobile service and signed up to have our numbers ported. Since then, our phones are not working and Verizon says once they get notified that you are cancelling your account, they automatically shut your phones off and then completely cancel you once the billing period is up, leaving us with no phones at all (we have no landline).

Our Sim cards are set to be delivered Tuesday and I need to know what, if any can be done to at the very least be able to get voice service with the Tmobile cards.

I can find older posts from 2013 about how to dial *#197328640# and go through an unlock procedure, but since my phone was bought August 2013 and now has Android 4.3 running I am also finding answers of people saying basically if you have 4.3 you are out of luck.

I am not new to flashing Roms or anything, I just need to be pointed in the right direction on what can and can't be done, like do I need to load a 4.1 Rom? I'm trying to at least have voice service until I can buy Tmobile phones if needed.

Thank you in advance for any information that can help.

Thanks for the info.

Once my SIM cards arrived, I just popped one in and it didn't work. I ended up grabbing a friend's phone and plugged in the following APN settings and got everything but MMS messaging (still limited to EDGE data though). I didn't have to root at all, but since then I have rooted and will be adding a custom ROM just to get rid of all the Verizon bloatware

Name: T-Mobile US
APN: epc.tmobile.com
MMSC:hxxp://mms.msg.eng.tmobile.com/mms/wapenc
MMS Proxy: 261.155.165.050
MMS Port: 8080
MCC: 310
MNC: 260
APN Type: default, sulp, admin, dun, mms
APN Protocol: IPv4/IPv6
APN Roaming Protocol: IPv4/IPv6

HapaKato said:

Moving to kitkat resolved my mms not sending issue, no idea why. I'm still pretty sure we're not going to get better than Edge, but I mostly use wifi so it hasn't been problematic for me.

Here's the APN I use on my S3, PacMan 4.4 3/31/14 Nightly (came built in)

Name: T-Mobile US LTE
APN: Fast.t-mobile.com
Password: ****
Server: *
MMSC: hxxp://mms.msg.eng.t-mobile.com/mms/wapenc
MCC: 310
MNC: 260
APN type: Default,supl,mms
APN protocol: IPv4
APN roaming protocol: IPv4

Click to expand...

Click to collapse

Must be something with the ROM cuz I can't get MMS fixed with those APN settings..... did you upgrade from an OTA 4.3?