I often pause my service when in a country where fi doesn't work well. Surprise - arrived at sfo and their free internet (the ONLY one available) didn't work at international terminal - not at baggage claim, not at departures, etc.
So found a kind soul who let me use his phone to call them - after 20 minutes and multiple verifications of who I am he said cannot resume my service has to be done from my phone!!! Asked him if I could do it from browser by signing in on another phone - he said yes - so I did that BUT account said I am not calling from my phone so had to send a verification text to my phone (the one that was paused and therefore wouldn't receive a text)!!!!!
No way to resume without wifi - which wasn't available anywhere (unless I bought a ticket and went to lounge inside security - not really possible with luggage, etc). Finally after an hour I someone who had a wifi hot spot and let me use it - Bingo - within 2 seconds I was saved.
SFO knows that their wifi has been not working for a long time for many phones (and also tried my laptop which got the same 502 error).
So can't call for a ride, or contact lyft or uber, etc without data - REALLY THINK FI SHOULD WARN that u CANNOT resume service unless u have wifi!