I travel regularly to Asia for work, and for some reason my T-Mobile prepaid international roaming works in some Asian countries and not others. It can't roam in Singapore, and doesn't register with any of the local carriers. A couple of months ago, I was previously able to do so. Was wondering if anyone else was having this problem.
I have checked the international roaming PDF, and Singapore is one of the supported countries with partner MobileOne (M1) on 900, 1800, 2100. The International Calling PDF I'm referring to is:
I have 2 lines, one on legacy Pay-As-You-Go, and the other on Simple Choice Prepaid $50/month. Both lines successfully roamed in Korea (SKTelecom) and Japan (NTT DoCoMo) without any additional configuration. I am able to receive texts and the occasional incoming call (did not pick up to avoid fees).
On a previous trip to Singapore in October 2016, I was successfully able to get on the M1 network, but not this time. The phone is unable to register with any of the local carriers in Singapore including M1.
I called T-Mobile Customer Service and gave them the number at the back of my T-Mobile SIM, I checked if international roaming is blocked (it wasn't), international roaming was included on my plan (it was), and finally I was issued a reference number but as of today it's still not resolved...
I've tried most of the usual troubleshooting tips. Switching phones (iPhone, Android, tried them all), testing different SIM cards, going into the Settings menu and manually choosing the network operator, switching between 2G, 3G and LTE mode. I confirm that the phones I'm using are unlocked since I'm able to use foreign SIM cards in them.
Was wondering if anyone had any ideas. Thanks in advance.