Roaming Issue in Serbia: Yettel Disconnect / H+ on MTS

[getsimon]

Hi everyone,

I'm currently abroad in Serbia and experiencing a very frustrating roaming issue with my EE line, and I'm hoping someone here might have some insights or have experienced something similar. EE Customer Service has been unable to resolve it so far.

Here's the problem:
My Samsung Galaxy S25 Ultra connects to the MTS network here, but only gets H+ (3G) speeds, which is very slow. EE has a roaming agreement with Yettel in Serbia, and Yettel offers much faster 4G/5G speeds. When I manually try to select Yettel, my phone connects for about a minute, and then immediately disconnects, forcing me back to MTS.

Crucial Diagnostic Steps I've Taken (and why it's so confusing):
* SIM Card Swap Test:
* I put my EE physical SIM into my wife's phone (which is also a Samsung Galaxy S25 Ultra). The exact same problem occurred – stuck on MTS (H+), disconnects from Yettel.
* My wife has an identical EE plan/contract to mine. When she puts her EE physical SIM into her phone, it automatically connects to Yettel with full 4G/5G speeds, no problem.
* When she puts her EE physical SIM into my phone, it also connects to Yettel with full 4G/5G speeds, no problem.
* Conclusion from this test: The issue follows my specific SIM card/phone number, regardless of the device. 

My Leading Theory (and why I think it's relevant):
A few months ago, I ported my number from Vodafone to EE. Given that the issue is specific to my line, follows my number, and isn't resolved by changing the SIM type, I strongly suspect there might be a lingering issue from the number porting process.

Could there be:
* Incomplete routing table updates for my number internationally?
* Conflicting or partially applied roaming profiles from my previous network?
* Some kind of "stuck" status on my line's roaming permissions due to the port?
It feels like my line isn't fully authorised or routing correctly to EE's preferred roaming partner (Yettel) in Serbia, forcing it onto a less optimal connection. My wife's clean EE line has no such issues, reinforcing this belief.

Has anyone experienced a similar issue, especially after porting a number to EE?
Does anyone have advice on how to explain this to EE customer service in a way that gets them to escalate to a higher technical tier who can investigate account-level provisioning and potential porting anomalies? I've already spent hours on the phone with basic troubleshooting.
Any help or insights would be greatly appreciated!

Thanks in advance.

[Schockwave]

Hello @getsimon ,

Welcome to the community,

Did you enable roaming on your account before going abroad? If you did not, then that would be the reason.

Did you receive the welcome message from EE?

[getsimon]

Yes I have. I spoke with EE before travelling and they confirmed all is set up. I spoke with them 2 times while abroad and they are unwilling to help or escalate this to a senior tech team for investigation. They literally told me "you are abroad, you are on your own on this, we can't do anything".

Very disappointing, I regret switching from Vodafone. 

[Schockwave]

Well, whenever I am abroad, not had a problem, but then I have not been to Serbia.

[bristolian]

I admire your methodical approach here.

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@getsimon wrote:

Could there be:
[snip]
It feels like my line isn't fully authorised or routing correctly to EE's preferred roaming partner (Yettel) in Serbia, forcing it onto a less optimal connection. My wife's clean EE line has no such issues, reinforcing this belief.

---

None of these theories would hold true, on various levels. Your basic permissions are clearly in-place, else you wouldn't be getting a connection in the first place.

Preferred/available network status is managed using multiple techniques, the issue probably lies in those.

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@getsimon wrote:

Does anyone have advice on how to explain this to EE customer service in a way that gets them to escalate to a higher technical tier who can investigate account-level provisioning and potential porting anomalies? I've already spent hours on the phone with basic troubleshooting.
.......

they are unwilling to help or escalate this to a senior tech team for investigation. They literally told me "you are abroad, you are on your own on this, we can't do anything".

---

Oh dear. If you're reporting a fault, there is an escalation process that results in a single-user INC fault being raised. Yours may depend whether this is seen as a fault, or just part of the roaming service.

Your next step would be the formal complaints process.