Carrier Settings
A small profile your phone downloads from each carrier on first activation. Configures APN, MMS, voicemail server, Wi-Fi calling endpoints, and carrier-specific menu strings. Updated automatically when carriers push new versions.
Carrier Settings (sometimes called "carrier bundle" on iOS or "carrier config" on Android) is a small configuration profile your phone downloads from the carrier when you first activate service or insert a SIM. It tells the phone how to talk to the carrier’s network in vendor-specific ways.
What it configures
- APN (Access Point Name) for data connectivity
- MMS proxy and gateway URLs for picture messaging
- Visual voicemail server credentials and URL
- Wi-Fi calling ePDG endpoints (the IPSec gateways for VoWiFi)
- VoLTE/VoNR enablement per-band
- Roaming partner lists and which networks are preferred
- Carrier-specific UI strings (the carrier name shown in the status bar)
Updates and version pinning
Carriers push updates to these profiles via the cellular signaling channel; the phone applies them automatically with a small notification ("New carrier settings available"). Each phone has a current carrier-settings version — on iOS this is at Settings → General → About → Carrier; on Android it’s usually under Settings → About Phone.
When switching carriers, especially when porting in or activating a new eSIM, the carrier-settings update happens automatically within a few minutes. If it doesn’t (you have data but voicemail/MMS aren’t working), the carrier-settings update is the most likely thing that didn’t happen yet.
Forcing an update: on iOS, toggle Airplane Mode and back. On Android, restart the phone. Both will trigger a re-fetch.