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Sporadic Service with VoLTE and LTE data enabled

Frequent Visitor

Sporadic Service with VoLTE and LTE data enabled

Hi,

I have an iPhone XS Max that was purchased unlocked from Apple. I have the esim feature activated from T Mobile and I am using Xfinity Mobile as a secondary line in the physical sim slot. I have the T mobile line set as the primary line and the data line. The Xfinity Mobile service works as expected if I have the Enable LTE option turned Off. If I enable LTE voice and data, the service becomes intermitent and sometime looses service. I would like to be able to leave the Enable LTE On for Voice and Data. I have already tried resetting network settings, restarting the phone and also putting it in airplane mode. Also there are no profiles installed. I am running iOS 12.1.4.

 

Thanks,

Valued Contributor

Re: Sporadic Service with VoLTE and LTE data enabled


@riley181 wrote:

Hi,

I have an iPhone XS Max that was purchased unlocked from Apple. I have the esim feature activated from T Mobile and I am using Xfinity Mobile as a secondary line in the physical sim slot. I have the T mobile line set as the primary line and the data line. The Xfinity Mobile service works as expected if I have the Enable LTE option turned Off. If I enable LTE voice and data, the service becomes intermitent and sometime looses service. I would like to be able to leave the Enable LTE On for Voice and Data. I have already tried resetting network settings, restarting the phone and also putting it in airplane mode. Also there are no profiles installed. I am running iOS 12.1.4.

 

Thanks,


As far as I know,  the dual sim support in iPhone is restricted to the type of carrier used for both sim; this means both the sim carrier should be either GSM or CDMA and they cannot be a mix and match.   Refer the Apple support page on this topic - https://support.apple.com/en-us/HT209044

 

To use two different carriers, your iPhone must be unlocked. Otherwise, both plans must be from the same carrier. If a CDMA carrier provides your first SIM, your second SIM won't support CDMA. Contact your carrier for more information. 

If you have an enterprise or corporate cellular service plan, check with your company administrator to see if they support this feature.

Also I thought Xfinity Mobile hasn't officially started supporting the dual sim yet in their network/devices.  Have they started the dual sim support?

Frequent Visitor

Re: Sporadic Service with VoLTE and LTE data enabled

This is not correct, as long as the phone is unlocked, the carriers can be different. You cannot have two CDMA carriers. Also, Xfinity does not need to support esim as long as the physical sim is being used, it is no different from putting the sim in any other compatible iPhone.

Official Employee

Re: Sporadic Service with VoLTE and LTE data enabled

riley181,  Are you able to use VoLTE when you have disabled the TMobile sim card? 


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Frequent Visitor

Re: Sporadic Service with VoLTE and LTE data enabled

After turning off the Tmobile line and using only the Xfinity mobile with data and voice LTE enabled, the service was a bit more reliable but still not good. I have 2 bars out of 4 sometimes it drops to 1 bar. If I turn off the LTE, I have 3 or 4 bars.

Official Employee

Re: Sporadic Service with VoLTE and LTE data enabled

After turning off the Tmobile line and using only the Xfinity mobile with data and voice LTE enabled, the service was a bit more reliable but still not good. I have 2 bars out of 4 sometimes it drops to 1 bar. If I turn off the LTE, I have 3 or 4 bars.

What about Data roaming? Is that activated?


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Frequent Visitor

Re: Sporadic Service with VoLTE and LTE data enabled

No data roaming is turned off.

Frequent Visitor

Re: Sporadic Service with VoLTE and LTE data enabled

So I have narrowed down the issue to wifi calling. When wifi calling is enabled and I am connected to a wifi network, the service is sporadic. If I turn off wifi calling, the service works as expected.

Official Employee

Re: Sporadic Service with VoLTE and LTE data enabled

Got it. We are aware of some issues caused when activating wifi calling on the iPhone models. We're working on a fix. 

 

Ken


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Frequent Visitor

Re: Sporadic Service with VoLTE and LTE data enabled

Ken,

Any update on this fix? I would like to get this issue resolved, my office is in my basement and I get poor service there, so this would really make a difference.

 

Thanks

Official Employee

Re: Sporadic Service with VoLTE and LTE data enabled

riley181, nothing yet. I'll be sure to update this thread when I get something. Sorry for the delay but thanks for your patience. 


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Official Employee

Re: Sporadic Service with VoLTE and LTE data enabled

Hey All, an iOS update has just been pushed OTA. Please check for this update and complete it if you can. Please let me know if the problem persists. 

 

ken


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New Poster

Re: Sporadic Service with VoLTE and LTE data enabled

I realize that this thread may be a bit old but I have a similar sporadic issue.

Background:
iPhone 11 Pro - Unlocked
AT&T Service on eSIM (Primary Voice and Data)
Xfinity Mobile Service on Physical SIM (Secondary Voice and Data)
Cellular Data Switching Enabled on both Lines.
VoLTE enabled on both lines.
WiFi Calling Enabled on both lines.
iOS 13.3.1

Phones being called are all iPhones
Dual SIM XS Max (T-Mobile Primary eSIM / Xfinity Secondary Physical)
iPhone SE Xfinity Mobile
iPhone 6 Plus Xfinity Mobile

I’ve been encountering issues which seem to be related to VoLTE or some type of Data Network Registration delay or error when making calls on my Secondary.(Xfinity Line) Theses issues do not occur all of the time but often enough to take note. The issue manifests in a few different ways. I’ll make a call from my secondary( xfinity line ) to another number on the xfinity network while I am connected to the primary AT&T cellular network. When this happens my AT&T 5Ge icon drops and the Xfinity LTE icon pops up in the corner. ( I expect this ) The phone is dialing/ringing and from here i’ve noticed 3 outcomes.
1.). If everything works as it’s supposed to the call connects, the voice connection is notably an HD connection, the LTE icon persists in the upper right corner of the phone and browsing and other internet traffic passes while on the call.
2.) The phone dials and rings the other phone and when the other user attempts to pick up the Call is disconnected and the receiver gets the call failed pop up.. Depending on how quickly they acknowledge the call failed message the calling phone may actually retry the call(as I believe it fails over) and succeed but not as an VoLTE call as the LTE icon disappears and the voice quality is notably not HD and no Internet traffic passes.
3.). The phone dials and rings the other phone for a few rings and then the LTE icon disappears, (ring sound quality drops) and the call is sent over the regular cellular network, I’m guessing the CDMA network as it’s Xfinity/Verizon. Again, no cellular data during the call and no HD voice.

When the LTE icon does disappear I’ve attempted to make a few other calls to see if it’s just an initial negotiation/registration delay but subsequent calls seem to just go over the regular cellular CDMA network and the LTE icon just disappears or maybe does not even come up after the initial call. I’ve been able to fix this by toggling the phone into and out of Airplane mode and then attempting to make the call again and then the LTE icons stays up in the corner and everything works as expected again until it doesn’t again.

I realize that this is probably not a very typical phone configuration with the dual SIM setup but figured I would ask the forum to see if anyone else has experienced something like this and if anyone knows why this is happening and if there is a more permanent way to fix this.

Thanks!