You came to the right place. I've used FI extensively in Kerala. Pre-covid, I was there at least every other month.

My experiences were mostly in Kochi and Trivandrum. If I recall (last trip was Jan 2020), I was able to choose between Airtel & Vodafone as my provider whilst there on FI's roaming. In general in Kerala, I found Airtel is more reliable. In the heart of the town (Think Kochi Marriot near Lulu mall) I got ~40mbps down on FI. In Trivandrum (at the downtown Hilton garden inn, I'd get around 20mbps-25mbps if memory serves).


Out near Kovalam, I'd get more in the range of 3-4mbps... worse if I went indoors.

Of course on the way too Kerala, I either went via Mumbai (where I always had great service at ~40-60mbps on Vodafone via FI). Other times I went via Qatar where I had great service in the qatar business lounge but didn't need it due to their wifi.

One Note... for some reason, every time I'd land in Kerala and turn my phone on after landing... I'd have great service for about 1 min, then it dropped off for about 10 min before it would come back. Usually by the time the plane got to the terminal, I'd have service again.

I used FI standalone most times... I've also used it in a dual-sim config on my iPhone with FI set as the data line. My additional data only sims also were great in my iPad.. worked flawlessly in Kerala. In fact, on iPhone, overseas tethering doesn't work, but for some reason I could tether off my iPad with the data only sim.

PS. If you have a dual-sim phone it might be worth giving Airalo a try. I've not had a chance to use them overseas, but it seems like a great deal/option for your usecase.