I have the A1901 model of the iPhone X which uses the Intel modem. This is my first Apple device that uses the Intel modem instead of the Qualcomm. This also happens to be the most problematic device when it comes to cell network connection that I have ever had from Apple, and in fact the most problematic that I have ever owned period. Before you go all "what's this guy talking about" hear me out and note that I am just trying to gather more information so that I can get Apple to assist in addressing the issue for me and anyone else that may be affected by this. I have now been working with Apple on this issue for about a week, quite intensively, and I am exhausting information that I can provide.
Both devices exhibit the same issue. They take an unusually long time to connect to LTE whenever they are in a less-than-perfect LTE coverage area, and when they are locked onto LTE and the signal quality degrades, they have difficulty down-switching to 3G in order to maintain a stable connection. In fact, more often that not, in a low LTE service area instead of going to 3G, the device will try to maintain LTE even if it does not work causing data to basically stop working. The only way to alleviate this issue is to manually turn off LTE and switch to 3G, then re-enable LTE once the signal recovers. As you can imagine, this is highly undesirable as it requires a tremendous amount of manual maintenance. This is even worse when VoLTE is used because with VoLTE the device would not even attempt to connect to 3G for outgoing calls, so even outgoing calling is blocked in this case.
This is not a carrier or SIM issue. It is an iPhone X issue, full stop. It does not occur with the iPhone 8 Plus, or an iPhone 6s Plus that I have. It also does not occur with the BlackBerry KeyOne Black Edition, the Samsung Galaxy S8+, or Essential PH-1. All of those devices were tested for the same type of issue and only the iPhone X exhibits this problem. I have also tried iOS 11.1.2, 11.2 beta 3, and 11.2 beta 4, all seemingly with the same problem.
Last but not least, under normal usage somebody would may not even really be aware that their device is having a problem. The reason why is because the device never actually drops the LTE signal to fall back to 3G, it just hangs on to it beyond - what seems to be - operational range. Using the service menu I have noted LTE still wanting to stay connected when the signal dips below operational values. Here is a chart that illustrates what is acceptable signal range very well...
https://forms.na1.netsuite.com/app/...icle=understanding-lte-signal-strength-values
![7%20%2825%29.jpg 7%20%2825%29.jpg](https://imore-data.community.forum/attachments/86/86359-daf199d412dc449d598b2da5ea7922d7.jpg)
On this device I am regularly seeing RSRQ < -20dB and SINR below 5dB.
I realize that this may have been a crazy read, and if you got to the end, congrats. Now, please see if you can take your A1901 (check by going to Settings > General > About and then tapping on the value next to Model heading) from a functional LTE service area to a bad LTE service area, like a basement, where there is enough signal to still get LTE but not enough to use it comfortably, and see if you can still use data, and see if the phone falls back to 3G successfully. Also, if you can take note of your RSRP at that time it would be great. You can see the RSRP by typing in *3001#12345#* into the dialier, calling it, and then navigating to Serving Cell Meas (measurements related to the tower you're currently connected to).
Thanks all and please post your findings below! I am going to try to do some measurements tomorrow in the area where I can reproduce the problem at will and see what is the device returning.
Both devices exhibit the same issue. They take an unusually long time to connect to LTE whenever they are in a less-than-perfect LTE coverage area, and when they are locked onto LTE and the signal quality degrades, they have difficulty down-switching to 3G in order to maintain a stable connection. In fact, more often that not, in a low LTE service area instead of going to 3G, the device will try to maintain LTE even if it does not work causing data to basically stop working. The only way to alleviate this issue is to manually turn off LTE and switch to 3G, then re-enable LTE once the signal recovers. As you can imagine, this is highly undesirable as it requires a tremendous amount of manual maintenance. This is even worse when VoLTE is used because with VoLTE the device would not even attempt to connect to 3G for outgoing calls, so even outgoing calling is blocked in this case.
This is not a carrier or SIM issue. It is an iPhone X issue, full stop. It does not occur with the iPhone 8 Plus, or an iPhone 6s Plus that I have. It also does not occur with the BlackBerry KeyOne Black Edition, the Samsung Galaxy S8+, or Essential PH-1. All of those devices were tested for the same type of issue and only the iPhone X exhibits this problem. I have also tried iOS 11.1.2, 11.2 beta 3, and 11.2 beta 4, all seemingly with the same problem.
Last but not least, under normal usage somebody would may not even really be aware that their device is having a problem. The reason why is because the device never actually drops the LTE signal to fall back to 3G, it just hangs on to it beyond - what seems to be - operational range. Using the service menu I have noted LTE still wanting to stay connected when the signal dips below operational values. Here is a chart that illustrates what is acceptable signal range very well...
https://forms.na1.netsuite.com/app/...icle=understanding-lte-signal-strength-values
![7%20%2825%29.jpg 7%20%2825%29.jpg](https://imore-data.community.forum/attachments/86/86359-daf199d412dc449d598b2da5ea7922d7.jpg)
On this device I am regularly seeing RSRQ < -20dB and SINR below 5dB.
I realize that this may have been a crazy read, and if you got to the end, congrats. Now, please see if you can take your A1901 (check by going to Settings > General > About and then tapping on the value next to Model heading) from a functional LTE service area to a bad LTE service area, like a basement, where there is enough signal to still get LTE but not enough to use it comfortably, and see if you can still use data, and see if the phone falls back to 3G successfully. Also, if you can take note of your RSRP at that time it would be great. You can see the RSRP by typing in *3001#12345#* into the dialier, calling it, and then navigating to Serving Cell Meas (measurements related to the tower you're currently connected to).
Thanks all and please post your findings below! I am going to try to do some measurements tomorrow in the area where I can reproduce the problem at will and see what is the device returning.
Last edited: