[Guide] Enable AT&T US HD Voice/VoLTE on non-supported W10M phones

[gchq]

It does say that, but, doesn't work. I tried it and it bricks the cellular modem and I had to reload a rom from PC to get it back. The modem files for dual sim are completely different than for single sim, there is probably a way to unpack the cab's in there and merge the single sim ones into the dual sim format but it's much easier to just get a single sim device. The dual sim stuff just really complicates things.
I've no idea on your Android question, never touched the stuff. To me using Android or iOS would be the same as using coke without a good high part.

I have say that I agree about iCrap and Android - the Essential I got just to upload cheques to Wells Fargo when they dropped support for the Windows phone with their app.

At the moment voice calls go to VoiceMail and as Visual Voicemail is data driven it still works and I can call them back from another phone. The lack of spam calls has been quite refreshing.

I'll look into getting a single SIM XL.

Edit

Looking around for a single sim XL I keep stumbling over forums where the poster was kicking off that the dual SIM doesn't work with Visual Voicemail. Interesting, mine worked with that from the get-go. I seem to remember that if someone booted up a new phone without a SIM inserted that was an issue, and problems with 4G.

 

[73blazer]

I'll look into getting a single SIM XL.

The single-sim RM1085 seems to be more prevalent in Europe. Do not buy the ebay "from china" ones, most of those are knockoffs and not real. I bought two brand new in box never used ones one from Jordan and one from the UK. There's lots of used ones out there too and the good part about a 950xl is if the screen is good, nothing else really goes bad except the battery which is thankfully easily replaceable.

 

[gchq]

I have say that I agree about iCrap and Android - the Essential I got just to upload cheques to Wells Fargo when they dropped support for the Windows phone with their app.

At the moment voice calls go to VoiceMail and as Visual Voicemail is data driven it still works and I can call them back from another phone. The lack of spam calls has been quite refreshing.

I'll look into getting a single SIM XL.

Edit

Looking around for a single sim XL I keep stumbling over forums where the poster was kicking off that the dual SIM doesn't work with Visual Voicemail. Interesting, mine worked with that from the get-go. I seem to remember that if someone booted up a new phone without a SIM inserted that was an issue, and problems with 4G.

Interestingly if I go to https://sim-usa.mobi/phone-compatibility-check/ the existing IMEI shows as Incompatible with AT&T but 100% compatible with T-Mobile - the 950 IMEI is the exact opposite, 100% with AT&T and incompatible to T-Mobile

It does say that, but, doesn't work. I tried it and it bricks the cellular modem and I had to reload a rom from PC to get it back. The modem files for dual sim are completely different than for single sim, there is probably a way to unpack the cab's in there and merge the single sim ones into the dual sim format but it's much easier to just get a single sim device. The dual sim stuff just really complicates things.
The only reason a single sim 950 works is because AT&T sold it in their store and had the right rom to work on their network with the VoLTE/HD Voice stuff. So...that is where the modem files came from and can be used on any phone with the same modem (x50 devices in theory).... I tried on a X3 and that phone is laid out all different, the modem files aren't even in the same directory. The modem is different so they likely wouldn't work anyway..etc..etc..
I've no idea on your Android question, never touched the stuff. To me using Android or iOS would be the same as using coke.

Interestingly if I go to https://sim-usa.mobi/phone-compatibility-check/ the existing XL IMEI shows as Incompatible with AT&T but 100% compatible with T-Mobile - the 950 IMEI is the exact opposite, 100% with AT&T and incompatible to T-Mobile.

imei.net check confirms that the 950 IMEI is RM-1105 which I believe IS the AT&T model

 

[73blazer]

They may at some point turn off the whitelist for VoLTE/HD Voice (or Enhanced 4g Services as they programmed into the Lumia 950) and just enable VoLTE on every device on the network as it's required anyway for voice and sms.... . That would negate the having to register a 950 IMEI with them for your hacked XL to work.
Keeping whitelists can be a pita for them.
One day when I have time to waste I might try registering an iPhone IMEI and see if I can get WiFi-Calling to turn on on my 950XL, I enabled all the registry for it and added the code, and I see it in my sim settings, but it does not work, I have a feeling it needs to be "enabled" with AT&T on their end. But I'm not sure if a different platforms IMEI will break everything or not.

 

[gchq]

They may at some point turn off the whitelist for VoLTE/HD Voice (or Enhanced 4g Services as they programmed into the Lumia 950) and just enable VoLTE on every device on the network as it's required anyway for voice and sms.... . That would negate the having to register a 950 IMEI with them for your hacked XL to work.
Keeping whitelists can be a pita for them.
One day when I have time to waste I might try registering an iPhone IMEI and see if I can get WiFi-Calling to turn on, I enabled all the registry for it and added the code, and I see it in my sim settings, but it does not work, I have a feeling it needs to be "enabled" with AT&T on their end. But I'm not sure if a different platforms IMEI will break everything or not.

One can hope
Incidentally, what settings do you have on your working XL for APN and MMS APN?

Apparently iCrap is a totally different ecosystem to Android and Windows. Why MS bailed them out is beyond me, but there it is and now we have it!

 

[73blazer]

Internet APN is "nxtgenphone" which is what you get when copy the new modem files from the 950 and VoLTE is activated.
There is no MMS APN, I believe that was a 2g setting no longer used. MMS had been routed via your data connection for at least a decade

 

[gchq]

Internet APN is "nxtgenphone" which is what you get when copy the new modem files from the 950 and VoLTE is activated.
There is no MMS APN, I believe that was a 2g setting no longer used. MMS had been routed via your data connection for at least a decade

View attachment 5585215

Interesting - those are the settings I have expect it's not the default

 

[73blazer]

If I view the APN it's just all dehighlighted, I can't change anything in it. The APN is filled out as nxtgenphone (lower case) but dehighlighted. I never changed anything related to these APN, they should get filled by the carrier once connected to their network. I think for 3g the apn listed a URL IIRC. But once I did the VoLTE, it changed to nxtgenphone and blocks you out from changing it. The AT&T Branded 950 also shows the same stuff I got here on my hacked XL when I had the sim in it.

 

[nate0]

I purchased a 950XL Single Sim version and it worked right away with the Puretalk SIM.

The only downside is that the version of windows 10 on the phone is very old and the windows update feature of the phone doesn't work. The store doesn't even work.

I thought that if I log in after a phone reset it would pull everything over?

I have a dual sim using the same windows account I was hoping to move everything over.

1. Is there a way to upgrade to the latest version of Windows 10 mobile
2. Is there a way to transfer all the apps from the dual sim to the single sim?

Thanks!

Have you tried the otc updater?

 

[gchq]

As an interesting update - 950XL Dual SIM now playing with AT&T without changing any config files.

1. Get an old AT&T branded 950 and ask AT&T to change the EMEI to that one

2. Head into settings > Cellular & SIM > SIM 1 Settings and click to add an Internet APN



Profile name = For unlocked non AT&T Devices 2 (I think this is just free text)

APN = nxtgenphone (case it would appear is important - uppercase doesn't work)

IP Type = IPv4

Check 'Use this APN for LTE and replace one from my mobile operator'

Save



The 950XL dual SIM now works with VoLTE and all other 4G features

The SIM 1 reading now shows AT&T 4G instead of AT&T LTE as before.

=================== Edit =======================

As Alice would say, curiouser and curiouser.

After a while it resets itself back to LTE and once again voice calls fail.

If I go back into Internet APN, misspell the APN and save, it drops the connection - I can then re-edit it to the correct name and once again it connects as 4G and everything works for a while

I have noticed that the SIM name changes from 'SIM 1' to 'ity=Impersonation Dynamic False' whilst it is working.

Confused? You won't be after the next episode of SOAP!

 

[gchq]

Last message has been edited and updated!

 

[nate0]

As an interesting update - 950XL Dual SIM now playing with AT&T without changing any config files.

1. Get an old AT&T branded 950 and ask AT&T to change the EMEI to that one

2. Head into settings > Cellular & SIM > SIM 1 Settings and click to add an Internet APN



Profile name = For unlocked non AT&T Devices 2 (I think this is just free text)

APN = nxtgenphone (case it would appear is important - uppercase doesn't work)

IP Type = IPv4

Check 'Use this APN for LTE and replace one from my mobile operator'

Save



The 950XL dual SIM now works with VoLTE and all other 4G features

The SIM 1 reading now shows AT&T 4G instead of AT&T LTE as before.

=================== Edit =======================

As Alice would say, curiouser and curiouser.

After a while it resets itself back to LTE and once again voice calls fail.

If I go back into Internet APN, misspell the APN and save, it drops the connection - I can then re-edit it to the correct name and once again it connects as 4G and everything works for a while

I have noticed that the SIM name changes from 'SIM 1' to 'ity=Impersonation Dynamic False' whilst it is working.

Confused? You won't be after the next episode of SOAP!

View attachment 5597559

View attachment 5597561

Yeah I used to do this with the IDOL 4s and 950 XL on T-Mobile all the time. The idol 4s ADC files allowed cool features to be unlocked for T-mobile on the 950xl but wifi calling only worked on 2.4Ghz. The volte was always solid. However at times there was inconclusive or incomplete sim lock/provisioning and the GUI burped with that sim_name since it obviously was waiting for the variable to populate.

 

[gchq]

Yeah I used to do this with the IDOL 4s and 950 XL on T-Mobile all the time. The idol 4s ADC files allowed cool features to be unlocked for T-mobile on the 950xl but wifi calling only worked on 2.4Ghz. The volte was always solid. However at times there was inconclusive or incomplete sim lock/provisioning and the GUI burped with that sim_name since it obviously was waiting for the variable to populate.

Is there a way to get it to stick with 4G instead of reverting back to LTE?

 

[nate0]

Is there a way to get it to stick with 4G instead of reverting back to LTE?

I have no idea. I have not used AT&T as a provider since 2018.

 

[maximum56]

Have you tried the otc updater?

Yes, I did it said no new updates. I assume the OTC works the way it used to where I don't need any local update files?

Thanks!

 

[nate0]

Yes, I did it said no new updates. I assume the OTC works the way it used to where I don't need any local update files?

Thanks!

Yes, it downloads the cabs locally then pushes them to the phone. Make sure you are using the version of otc updater found here on xda because the one provided by Microsoft fails due to the version of authentication it uses. I personally would reflash the original ffu and update all from the otc updater from scratch. Could be something broke in Windows Mobile. What version did it end up on?

 

[maximum56]

Good to know concerning the OTC, I have one from MS. Will track it down here. Do you have a location for the CABs? I assume the instructions for the FFU are somewhere on here?

I factory reset the phone and it never was able to download updates in the normal manner so it is stuck on a real old windows 10. I did some snooping on the phone and in the about it says this phone is a prototype and don't resell it, lol. We shall see if that is an issue. I noticed with you reboot the phone it has tiny text in the corner that my other 750's don't have. WP has the kids corner and the store is very old and it won't connect.

Thanks so much for the help!

 

[nate0]

Good to know concerning the OTC, I have one from MS. Will track it down here. Do you have a location for the CABs? I assume the instructions for the FFU are somewhere on here?

I factory reset the phone and it never was able to download updates in the normal manner so it is stuck on a real old windows 10. I did some snooping on the phone and in the about it says this phone is a prototype and don't resell it, lol. We shall see if that is an issue. I noticed with you reboot the phone it has tiny text in the corner that my other 750's don't have. WP has the kids corner and the store is very old and it won't connect.

Thanks so much for the help!

Do not update it. If it is proto then it might be running a special version of FW and W10M. You CAN update it you just will lose any Proto features or anything else related to that special FW. Also if it is a Lumia 750 then there will be no updates on the standard production branch since the 750 was for internal use and utilized developer internal branches for deployment.

 

[z_row]

I have a Dual Sim 950XL that I booted back up after gchq mentioned he was having success. I find I have to alternate APNs once or twice a day to reset the SIM provisioning. Hoping this will go away as I really don't know if it is not connected until an outgoing call is immediately dropped (incoming calls will go straight to VM). I am using Red Pocket NVMO as my ATT carrier. Visual Voicemail has not worked since the 3g shutdown in my area (early Feb of this year)

 

[Old_Mil]

Just curious if anyone currently has a 950XL in the United States that is functioning with VoLTE on T-mobile or ATT after the 3g shutdown.

I'm currently using a 640 LTE RM 1073 with T-mobile Windows 8 that drops back to 4g or 2g for voice calls and maintains an LTE connection otherwise.