VoLTE APN settings for T-Mobile's MVNOs SIM cards with MNC 240 (as of December 31 2022)
If you have SIM card of one of T-Mobile's MVNO with MNC 240 (Lycamobile, Freedompop, Ultramobile, Tello etc.) and VoLTE does not work on your phone, try this: Add new ims endpoint with following parameters: Name: ims APN: ims APN type: ims MCC: 310 MNC: 240 (or 260 if your SIM's MNC is 260, but MNC 260 SIMs usually do not have VoLTE issue) Protocol: IPv6 Roaming Protocol: IPv4 Bearer: LTE , IWLAN (or just LTE if you cannot add IWLAN ) Last line (Bearer) is very important: it is a key to VoLTE. You should set it at least to LTE to enable VoLTE. Second value IWLAN seems to be responsible for VoWIFI, but I couldn't enable Wi-Fi calling even after adding IWLAN to Bearer. Just create this APN but do not set it active. After setting Bearer: LTE VoLTE started to work with Freedompop/Tmobile SIM and Tello SIM (both MNC 240) on my old Blu R1 HD (Android 6) and Tracfone's unlocked (and T-Mobile compatible) Samsung A10E. Tello support page is not mentioning Bearer attribute and ...