After arriving in Hong Kong, I received the helpful T-Mobile text message telling me I had data roaming available:
"Welcome to Hong Kong! Your T-Mobile plan gives you unlimited data at 2G speeds, calls at 20 cents/min and free texts."
Text messages and phone calls were working, but cellular data refused to connect.
Troubleshooting steps I tried:
- Confirmed data roaming is on
- Put phone in airplane mode for 1 minute
- Restarted phone
- Tried manually connecting to every carrier. Only the automatically selected one worked
- Enabled roaming via USSD code: #766#
- Tried manually specifying each network type (2G, 2G/3G, 2G/3G/4G)
- Tried my T-Mobile SIM in a different phone (worked)
- Tried a local SIM from the roaming carrier (Hutchinson 3) in my phone (worked)
- Tried a different T-Mobile SIM, that I know works, in my phone (didn't work)
- Asked T-Mobile if there was any block on my number for international roaming (nope)
There's a known issue with the LG G3 phone
With the problem finally understood, several sites mention how to manually enter an APN which enables roaming. The steps are:
Open Settings > Mobile Data > Access point names Copy down the settings of the currently selected Access Point Create a new Access Point with:
- Name = RoamingAPN
- This can be any name
This worked for me and hopefully will help other HTC 10 owners.