Phone function on an Android 16 tablet gone, always say "network busy"

Question

I have just received a new Teclast T65 tablet with Android 16. If you google "Teclast t65 iD mobile sim card", you can see:

The Teclast T65 (including Max and Plus models) features a dual Nano-SIM tray. It fully supports 4G LTE from UK providers like ID Mobile. Because ID Mobile runs on the Three UK network, the tablet must support Bands 3 (1800MHz) and 20 (800MHz)—which the T65 provides.

I inserted the old sim card into the tablet, Mobile data worked but no phone function. I tried all methods such as reboot, even reset mobile network settings. All no use. However, when I insert a O2 sim card and Vodefone sim, they worked no problem. Therefore, it must be problem due to the iD mobile sim.

I went to Currys, they say they do not support iD mobile. They told me there is someone from carphone warehouse can give me a new iD mobile sim. I activated the new sim card, problem is the same.

I checked the tablet information (see photos). Any help will be appreciated.

Owethu M · Answer

Hi ​@simon1955,Thanks for providing the detailed information and the screenshotthat’s really helpful.From what you’ve described (data working, but “Voice Service: Out of Service” on the tablet), this points to a specific limitation rather than a SIM fault.What we can see from your device infoMobile data is connecting successfully on LTEThe SIM is registering on the networkHowever, voice service is not registering (IMS not registered / Out of Service)This is why calls and standard mobile telephony features are not workingImportant clarificationiD Mobile SIMs are designed and fully supported for use in mobile handsets. While data may work in tablets (like your Teclast T65), voice services rely on VoLTE (4G Calling) being fully supported and provisioned on the device.What’s happening here is likely:The tablet supports LTE data bands (which is why internet works), butIt is not fully compatible with iD Mobile’s VoLTE/voice configuration, so the network cannot register the voice serviceThis results in “Out of Service” for calls even though data worksWhy other SIMs appear to workOther networks (such as O2 or Vodafone) may still allow legacy fallback or different VoLTE provisioning methods that the tablet accepts, whereas iD Mobile requires proper VoLTE registration for voice services.What you can try (troubleshooting)Even though this is most likely a compatibility limitation, you can try:Go to Settings > Mobile NetworkEnsure Preferred network type is set to LTE/4G (or LTE/WCDMA if available)Go to Access Point Names (APN) and reset to default settingsRestart the tabletReinsert the SIM and test againImportant checkPlease also test your iD Mobile SIM in a compatible handset (phone).If voice works in a phone → SIM is fine, device limitation confirmedIf voice does not work in a phone → we would then investigate the SIM/account side furtherSummaryBased on the logs and behaviour, your SIM is working for data, but the tablet is not properly registering iD Mobile voice services. This is consistent with a device compatibility limitation rather than a SIM fault, and a replacement SIM would not resolve the issue.If you’d like, we can also help check whether your specific tablet model has any confirmed VoLTE compatibility with iD Mobile.Owethu