Unable to do International Roaming in Singapore (SGP-M1)


    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.

      All replies

      • tmo_mike_c

        Greetings and thanks for posting eightyhertz.


        You've done an awesome job being so thorough with your testing and that's rough you've still being having trouble. I'm curious what happens when you tried to select the carrier manually? Did you get an error, and if so, what did it say? You mentioned you received a reference number the last time you called. That sounds like to me that you may have filed a Trouble Ticket. If it was, those can take up to 72 hours to get a response, but you can have a Tech Care rep look it up and give you the rundown of the ticket's status.

        • eightyhertz

          Unfortunately, I just called customer service, and they are unable to find the ticket associated with the reference number they previously gave to me.


          I repeated my question and they were unable to resolve the problem before the call dropped. I was directed to the "calling plans" department, and I was first informed that the plans do not have international roaming, which conflicted with the information I was provided in my Oct 24 2016 call that the plans did have international roaming. I did not change the configuration of the plans.


          This also conflicts with the fact that I am able to register on the network in all countries I have visited so far such as Korea and Japan. After around 40 minutes on the phone, I was directed back to the technical department.


          Unfortunately, this has been extremely frustrating for me and I have spent a significant amount of money on an international Skype call. I really need the phone line to work.

            • tmo_chris

              Okay eightyhertz, I did a bit more digging on this and I think I found out what the problem is.


              In your specific situation you are able to roam in some countries but not others which means that your account is set up correctly and there is nothing that would prevent you from connecting to a roaming partner network.


              The problem is that we cannot guarantee services from the 3rd Party roaming carriers as the roaming agreements can change without notice. Some roaming agreements with certain countries only allow for certain features to be used, not all countries are bilateral and can support normal T-Mobile features and services. Since you have prepaid service with the Pay as you go and Simple Choice pay in advance, the roaming partner must support prepaid services in order for your service to work there. I looked as SK Telecom and the agreement does support prepaid services. When I looked at Singapore, the only carrier we have an agreement with as of now is StarHub Mobile Pte Ltd and they do not support prepaid services.


              I know this is not the answer you were hoping for but I wanted to make it transparent as to why you are no longer able to roam in Singapore.

            • junyutan

              The reason why you can't roam in Singapore is because in April 2017, M1 discontinued all 2G networks, SGP-M1. T-mobile has to recontract terms with the carrier to use their 3G networks.