How to Fix WiFi Calling Dropping on Android: VoWiFi Settings, SIP ALG, and Carrier Provisioning Fixes

WiFi Calling (officially called VoWiFi — Voice over WiFi) routes your phone calls over your broadband connection instead of the cellular radio tower. When it works, it delivers crystal-clear calls even in a basement or rural area where cell signal is weak. When it drops, the experience is worse than a bad cell call because the handset may not seamlessly hand back to LTE/5G in time to save the call.

The root cause is almost never your WiFi speed — VoWiFi requires less than 1 Mbps. The real culprits are SIP packet mangling by your router, a stale IMS registration, or a carrier provisioning flag that was never set. This guide walks through each fix in order of how commonly it solves the problem.

Fix 1: Verify WiFi Calling Is Properly Enabled

Before diving deeper, confirm the feature is actually turned on and set to the right preference mode. The settings path varies by manufacturer:

• Samsung (One UI): Settings → Connections → Wi-Fi Calling → toggle On, then tap Wi-Fi Calling Preference and set it to Wi-Fi Preferred.
• Google Pixel: Settings → Network & internet → Mobile network → Wi-Fi Calling → toggle On.
• OnePlus / OxygenOS: Settings → Mobile Network → Wi-Fi Calling → toggle On.
• All other Android: Settings → Connections (or Network & internet) → Mobile network → Advanced → Wi-Fi Calling.

If the toggle is greyed out and cannot be enabled, the issue is carrier provisioning (see Fix 6 below).

Fix 2: Check IMS Registration

VoWiFi runs on top of the IMS (IP Multimedia Subsystem) framework. If IMS is not registered over WiFi, calls will either fail silently or fall back to LTE. Android includes a hidden diagnostic menu that shows live IMS status.

Dial *#*#4636#*#* on your dialer. Tap Phone information (repeat for SIM 2 on dual-SIM devices). Scroll down to the IMS section — it should display Registered next to both IMS and VoWiFi. If it shows Not Registered, toggle Airplane Mode on for 15 seconds and back off. Wait 60 seconds and check again. Persistent “Not Registered” status points to a router firewall issue or a carrier provisioning problem.

Fix 3: Disable SIP ALG on Your Router

SIP ALG (Session Initiation Protocol Application Layer Gateway) is a feature built into most consumer routers that tries to “help” VoIP calls cross NAT boundaries. In practice, SIP ALG rewrites SIP packet headers in a way that is incompatible with most carrier VoWiFi implementations, causing dropped calls, one-way audio, and failed registrations.

Disabling SIP ALG is the single most effective fix for WiFi calling dropouts on Android.

How to Disable SIP ALG by Router Brand

• ASUS: Advanced Settings → WAN → NAT Passthrough → set SIP Passthrough to Disabled.
• Netgear Nighthawk / Orbi: Advanced → Advanced Setup → WAN Setup → uncheck Disable SIP ALG.
• TP-Link (Archer): Advanced → NAT Forwarding → ALG → toggle off SIP (VoIP) ALG.
• Eero: Currently no exposed SIP ALG toggle; as a workaround, enable VoIP Passthrough in eero Labs if available, or place a third-party router behind the eero in bridge mode.
• Xfinity/Comcast gateway: Gateway → Advanced → Port Forwarding → there is no SIP ALG toggle; call Xfinity support and ask them to disable SIP ALG on the gateway remotely.

After saving the change, reboot your router and toggle WiFi Calling off and back on in Android settings to force a fresh IMS registration.

Fix 4: Enable VoIP Passthrough and Check NAT Ports

Some routers expose a separate VoIP Passthrough or H.323 Passthrough option in the firewall or ALG settings — enabling this tells the router to leave SIP and RTP packets alone. If your router has it, turn it on.

Additionally, VoWiFi uses the following UDP ports that must not be blocked: 500 (IKEv2 key exchange), 4500 (NAT traversal / IPSec), and 5060 / 5061 (SIP signaling). Most routers allow these by default, but if you have a strict custom firewall or are behind a double-NAT, verify these ports are open. See our guide on fixing double-NAT if your router is behind another router.

Fix 5: Force IMS Re-Registration With Airplane Mode

Even after fixing the router, the Android IMS stack may continue using a stale, broken registration. Force a clean re-registration:

1. Open Settings and toggle Airplane Mode ON. Wait 15 seconds.
2. Toggle Airplane Mode OFF. Reconnect to WiFi.
3. Wait 60 seconds, then make a test call.

If calls still drop, try removing the SIM card, waiting 10 seconds, reinserting it, and rebooting. This resets the device’s carrier provisioning cache and forces the phone to pull fresh VoWiFi parameters from the network.

Fix 6: Request Carrier Re-Provisioning

WiFi Calling must be enabled at the carrier account level, not just on the device. If you recently switched plans, ported your number, or replaced your SIM, the VoWiFi provisioning flag may not have been applied to your line.

• T-Mobile / Metro by T-Mobile: Dial #932# to check WiFi Calling provisioning status. If it returns an error, call 611 or use the T-Mobile app to request a line refresh.
• AT&T: Call 611 and ask support to push a “device profile update” to re-provision VoWiFi on your line.
• Verizon: In My Verizon app, go to Account → Manage Device and toggle WiFi Calling off and on. If still greyed out, contact support to re-provision.
• Google Fi: WiFi Calling is always on for Fi subscribers — if it’s missing, reinstall the Google Fi app and run the setup wizard again.

Carrier provisioning issues often present as a permanently greyed-out WiFi Calling toggle or a toggle that turns on but never shows “WiFi Calling” in the status bar, even on strong WiFi.

Quick Checklist

1. Enable WiFi Calling in Android settings and set preference to “Wi-Fi Preferred.”
2. Dial *#*#4636#*#* and confirm IMS shows Registered.
3. Disable SIP ALG in your router’s ALG or NAT settings.
4. Enable VoIP Passthrough if your router exposes that option.
5. Toggle Airplane Mode to force a fresh IMS registration.
6. Contact your carrier to re-provision VoWiFi if the toggle is greyed out.

If calls still drop after all six fixes, the issue may be specific to your Android version. Check for a pending system update in Settings → System → System update, as carriers periodically push VoWiFi bug fixes via OS updates. For more on optimizing your router for voice and video, see our guide on fixing WiFi calling generally and our roundup of best routers for working from home.