iPhone 17 Pro Max, Dual SIM (physical BSNL + Airtel eSIM), India. - Only one sim active at a time

iPhone 17 Pro Max, Dual SIM (physical BSNL + Airtel eSIM), India.

When one line has an active network/data, the other line goes to No Service completely — no calls, no SMS, no data. When I switch to another SIM, the first one goes to no service. Tried APN reset, a carrier update check, and a network settings reset. Can you help?

Posted on Sep 17, 2026 3:42 AM

1 reply

WheelieNick

Level 9 (74,110 points)

Sep 17, 2026 4:09 AM in response to Potatolaaa111

This issue is a known dual-LTE/5G modem conflict where older network handshakes (like BSNL's legacy bands conflicting with a primary Airtel LTE/5G connection) overload the phone's baseband processor, causing complete signal drops on the alternate line.

Quick Workaround

Change BSNL Network Mode: Go to Settings > Cellular > BSNL > Voice & Data and manually force it to 3G or 2G instead of LTE/5G, while leaving Airtel on LTE/5G.
This stops the dual-LTE conflict and usually keeps both lines concurrently reachable