There have been many cases of users not able to use mobile data or reporting that voice calling is not working on their device. Most likely these issues arise from cellular carrier defaults being inaccurate, and thus changes to the SIM and APN (“Access Point Names”) configuration are needed. The defaults for each carrier come from our upstream, LineageOS, but these defaults could be outdated should carriers make changes on their side that the LineageOS developers are not aware of.
This guide will note several steps to diagnose and hopefully fix any issues you may have.
Steps 0-3 address settings changes you may need.
Steps 4-5 are helpful to confirm voice calling may be disabled, which may indicate a settings change is still needed in the prior steps, or can at least give you confirmation that the voice network is not working and give you details to communicate back to your carrier.
Step 0: Enable “Mobile Data”
Before getting into the settings adjustments, first ensure that mobile data is enabled on your device. Go to “System Settings > Network & Internet > SIMs” and make sure it is enabled as below:
Step 1: SIM Settings
Next, tap on your SIM name (“T-Mobile”) in the the prior screenshot, and scroll down a bit to ensure that the “VoLTE” switch is enabled if it is present. “VoLTE” is “Voice over LTE” or more commonly just “4G / 5G voice calls”. Many carriers have been discontinuing their 3G or “GSM” networks in the past few years, meaning that if VoLTE is not enabled then you will not be able to make or receive phone calls.
In addition, if you happen to know that your carrier does not have a working 3G network anymore, then make sure that your “Preferred Network Type” is not set to 3G.
After you have these settings confirmed, you can then enter “Access Point Names” at the bottom.
Below is a screenshot of the items mentioned in this step.
Step 2: APNs
After opening “Access Point Names” you will find a list of the APNs on the phone. In my screenshot, the default of “T-Mobile US” is not correct, as I use US Mobile, a MVNO (network reseller) that uses the T-Mobile network. So my APN settings need to be for US Mobile even though T-Mobile was set as the default. If you need to create a new APN you can use the “+” at the top. You activate your current APN by simply tapping the circle to the right of it.
Step 3: APN Configuration
In your default APN (if you only have 1) or in your newly created APN, once you tap on its name in the prior screenshot, you then can see its detailed values. Most important here are the following fields:
- APN - required
- Proxy - optional depending on carrier
- Port - optional depending on carrier
- MMSC (for MMS messages) - optional depending on carrier
- APN Protocol - IPV4/V6 (default if not set) or IPV4 or IPV6 depending on carrier (not showing in screenshot)
- Network Type - may not be set, but again if you know 3G is disabled in your location, you can set to “LTE, NR” for 4G / 5G only.
All of these settings would need compared against your carrier’s documentation. So please find their information online or contact them for specific settings they require.
Once you make a change to these settings, SAVE (top right), and make sure it is active (See step 3 above), then often a Reboot is often the easiest to ensure the settings have been applied and your network is re-initialized.
After ensuring your APN settings are correct, you should at least have mobile data working. If you have Mobile Data but not voice calls, then we can check a few more things. But if you do not have mobile data working, then likely steps 2 and 3 above are where you need to keep trying to solve the issue, in collaboration with your carrier or another phone that may be working (you can use the above steps to reference the correct settings on a working phone).
Step 4: Phone Information
If you are here, then you have mobile data working, but no voice calls. In this case, we will go a bit deeper to check on the situation. In your Phone Dialer, dial *#*#INFO#*#* (INFO is 4636).
A screen will pop up, on which you can tap “Phone Information (V2)” if on iodéOS 7 or newer. (prior versions will be similar but will only have “V1” and thus the layout will be slightly different).
Note here on the default “Data & Network” tab you can see that “Data Service: Connected” and “Voice Service: In Service”, with “Voice Network Type: LTE”.
If you do not see these confirmations, then it confirms there is an issue as you already know about! Once again you can “Set Preferred Network Type: NR/LTE” to ensure only 4G/5G are used. This may be needed if 3G is being phased out by your carrier but is not fully offline yet, but is essentially partially broken as they phase it out.
There isn’t a lot else you can change here, it is more of a confirmation that things are connected or not. Note at the bottom I can see that my “MCC / MNC” is “310 / 260” which is unique for the carrier and confirms I am connected to their network.
Step 5: IMS Information
As a further confirmation of the current settings, tap on the “IMS” tab from the “Phone Information (v2)” screen opened in Step 4 above.
IMS Registration is foundational for VoLTE. So “IMS” must be active before VoLTE can be established. But the key here is that you want to confirm if “Voice over LTE” is available.
Note you can also see if VoWifi (“Voice over Wi-Fi”) is enabled. VoWifi is beyond the scope of this guide.
Wrap-up
Hopefully changes in ##Steps 0-3## resulted in your device now working with mobile data and voice calls.
If you followed along and still have non-functioning voice calls (confirmed with Steps 4-5), you will need to contact your carrier and have them check if there is any block on your device.
Verizon and AT&T in the USA, for example, have very restrictive device “white lists” which do not allow Fairphone, Brax, or Shift phones to register on their network since these phone manufacturers do not have established agreements to allow their devices on the network.
Such a restrictive “carrier white list” is based on the device, not the ROM / OS. This means that a Google Pixel 8 with stock Google software is seen the same by them as a Google Pixel 8 with iodéOS. As a Pixel 8 is on their “white list” it means it can be used regardless of what OS is installed on the phone.
If you continue to have issues, please reply with your phone model, OS version, and mobile carrier details (preferably with a link to your carrier’s website).