Strange: why are 2 SIMs behaving differently in the same router?

[littlesheep]

I have 2 different EE 5G SIMs. One is a prepaid Scancom EE SIM. The other is the SIM in my iPhone.

When I put the prepaid SIM into my Huawei 5G router it only gives me 4G and reports the connection as "BT".

When I put my phone SIM into the Huawei to test it, it gives me 5G and reports the connection as "EE". I get a strong 5G signal.

But here is where it gets really weird. If I put the prepaid SIM into my phone, it gives me 5G. So I know 5G is enabled and working on the prepaid SIM.

If I look at the network list on my router, using the phone SIM I get:

• EE 4G
• vodafone UK 4G
• O2 - UK 4G
• 3 4G
• EE 4G

(There are 2 different EE towers in range)

The network list for the prepaid SIM is:

• BT 4G
• vodafone UK 4G
• O2 - UK 4G
• 3 4G
• EE 4G

One of the EE towers seems to be labelled as "BT" but only when using the prepaid SIM.

I realise that BT now own EE. But why would 2 SIMs behave differently like this? There must be a reason why one SIM reports a given tower as "BT" and my phone SIM reports that same tower as "EE"?

Anyone have any clues what might be happening here? 

[XRaySpeX]

EE's PAYG (prepaid) SIMs only do 4G but what's Scancom?

---

@littlesheep wrote:

When I put my phone SIM into the Huawei to test it, it gives me 5G and reports the connection as "EE".

---

contradicts:

---

@littlesheep wrote:

If I look at the network list on my router, using the phone SIM I get:

• EE 4G
• vodafone UK 4G
• O2 - UK 4G
• 3 4G
• EE 4G

---

[bristolian]

EE's radio sites are labelled with the MNC/MCC combination of 234-30, which is the old T-Mobile code. EE SIMs then map that to "EE"

Individual SIMs have their own mapping table, and label networks accordingly. This is how MVNO's know to identify their host network as "Tesco Mobile" or whatever else.

[littlesheep]

I believe the 5G network here is deployed in NSA (non-standalone) mode, so the towers are still listed as 4G. 

[littlesheep]

Ah OK that makes sense. Explains why one SIM reports the tower as EE and one as BT. Could it be that newer EE SIMs are re-branding as BT now? Either way it seems that this should not affect the band or network speed, right?

[bristolian]

The radio technology in use (2G, 4G, 5G) doesn't factor in the MNC/MCC broadcast.

Neither does any speed issue feature.

[littlesheep]

Actually I now think it's just random: sometimes it finds 5G and sometimes it doesn't, not related to which SIM. Perhaps just a fluke that over about 6 tests it was always the phone SIM that found 5G and the Scancom SIM that didn't, causing my mind to see a pattern that isn't there.