International roaming caller ID not working

  • 4 September 2018
  • 13 replies

I am in Greece.  All incoming roaming calls from the US show as either French or Italian numbers or No Caller ID.  This has been going on for 3 weeks and has never happened in previous trips.  I have called repeatedly t-mobile but nothing has been rectified.  Any suggestions?

13 replies

Caller ID is not guaranteed when roaming. Have you tried changing the carrier you are roaming?

This is my 6th trip to Greece with t mobile. Caller ID worked fine all five previous times

the local carrier COSMOTE is a subsidiary of Deutche Telecom which owns t mobile, so it is very ironic that caller ID does not work.

I suspect that the reason is that the calls are being forwarded through European numbers for cost saving purposes but this is completely unacceptable when it results in malfunctioning caller ID

By the way, when I make international calls from the states, my US number shows up as a European number  to the people I call. These problems are completely unacceptable and I will have to change carrier if the problem is not immediately resolved.

So, have you tried to roam Vodafone or Wind? What happens?

It does not allo me to connect to either.   When I go to manual network selection, I can see both Vodafone and Wind but when I select either of them it says no service.

Well, it was a thought. Don't know how to help you with that caller ID problem or what might have caused it. BTW, I'm just a customer, like you, not an employee.

Does your phone use LTE for making calls in Greece or does it fall back to 3G? I'm not sure how roaming calls over LTE are processed. I used to have a pretty good grasp of the theory on the handling of GSM and UMTS calls. For GSM and UMTS calls, the phone is assigned a temporary local number, which is passed to T-Mobile's switching system and the call is forwarded to that number. That would be a Greek number. I have no idea how a French or Italian number would get into the process.

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Wow, that's really strange. Is this happening with US numbers you have saved in your phone? I'd say filing a ticket for our engineers is the next step, but I'm curious about exactly what you were told after you called.

I am in the States now but I believe it was 3G. Also please keep in mind that when I do call a Greek cell number from the states, my t mobile number does both show up. Instead a different European number from various different countries shows up, so people have no idea that it is me calling. Only when I call land lines by US number shows up correctly.

This is happening with all US numbers whether saved or unsaved. I have repeatedly called customer service. Some representatives said they would forward the issue, some said they are sorry. One called me back after attempting to solve the issue but the problem remained.

Userlevel 6
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That's super sad the issue's still happening. How long ago was the call back? After you told them issue was still happening, were you given info about getting the issue resolved? Most times the ticket would need to be updated and escalated if the issue continues.

I found these answers:

Muhib Afzal, OD | HR Coordinator at MTN Afghanistan (2008-present)

It is due to SIM box. Simbox or Interconnect Bypass Fraud is one of the most prevalent frauds today, costing the industry some USD3Billion. Calls made via the internet are sent to Simboxes (machines that house SIM cards) which redirect this illegal VoIP traffic onto mobile networks. Fraudsters effectively bypass the inteconnect toll charging points to exploit the difference between the high interconnect rates and the low retail price for on-network calls, thus avoiding payment of the official call termination fee of an Operator or MVNO.

Anton Dushko, lives in Saint Petersburg, Russia

Because your provider cuts expences (one may say “tries to make calls cheaper for you”, but that's just the flip side) and routes your call via some substandard route, like cheap VoIP gateway in recipient's country. The backbone provider that gateway is connected to may prohibit gateway owner from landing international calls, but they do it anyway, without putting your number to “caller’s number” field when the call is established, to avoid getting caught.

Some providers may give you several choices of routing with varying quality and cost, others just route your calls as they wish (including that not-quite-legal gateways for some destinations). In the former case it may be possible to select default route used when you just dial the number, or/and you may select what route to use for the call by dialling some prefix before the actual number.

If these answers are correct, this situation is completely unacceptable.  Nobody knows it is me when I am calling from the States to Greece and I have no idea who is calling me when I am travelling in Greece.  This needs to be corrected immediately or I will file a complaint with the FCC.

Hi all, I have the same problem!!!  I have T mobile USA number and I chose it because of the best rate for calling to my country - Poland. Everything has started January this year - when I'm calling to friends or family, they see my number as some random number within European Union (Holland, Romania, Hungary, Ireland, etc etc etc). So many times I was talking with customer support and it still isn't fixed. People are afraid picking up my calls, because they think it is scam. I disabled WiFi calling and it didn't helped. Correct caller ID is a most basic function you may expect from mobile carrier.

What are the next I should take? Should I reach FCC as well to raise this issue priority?

Thanks for helping me!

Was this issue ever figured out, I've been aware of this for at least 5 years now?

Hi All- I am also having the same problem.  And I am reading on this thread that issue has been around for more than 2 years? Seems really crazy for TMobile not to address this. It appears that :


While on  international roaming, personal and business calls  from USA have been coming in as random international numbers (Bulgaria, Greece, Croatia, Germany, France, etc). Sometimes I  do pick up, as a test, and realize it  is someone I do need to talk to! But more often I do not pick up because it might be scam and do not want to be charged  for a  random call without proper Caller ID.

So, it is a HUGE BUSINESS AND PERSONAL  LIABILITY  not to  know who is calling you. Aside from possible business loss,  what if there was an emergency back home (someone dies, gets in accident, is at hospital etc etc)  and you did not pick up???  

How can T-Mobile address this?

Or does everyone need to change carriers?