Performing a SIM swap - what happens to the old number?

[biscuits99]

Not strictly an O2 query, as its for Tesco Mobile in my case, but I was just wondering about this process.

I had a very old (around 2012 or so) full size PAYG Tesco SIM which was working fine, I then bought a new phone and ordered a new nano SIM from Tesco on PAYG.

On the new nano SIM I paid £10 and activated it, then ran through the SIM swap process:

This worked and the original number ported to my new Nano SIM.

My question is what happened to that number and the credit that was on the nano SIM?

And as I just needed to provide the SSN of the nano SIM, if I found someone else's SSN, could I just 'overwrite' their number - I don't remember the nano SIM number asking me if it was ok to proceed, that check only went to the original number I kept.

I mean, not an issue here as the process worked, but a bit odd it just seems to overwrite a number without checking?

[pgn]

Community guides for moving numbers below for ref.

Guide: Sim Swap: a mini guide 2017 update and Guide: Migration & porting into O2  - the number has to match the SIM SSN - the old number that was on the SIM you have swapped to goes back into the available pool of numbers for eventual reuse @biscuits99 

[biscuits99]

Thanks for the info about the number going back to a pool. Do you know what happens if someone finds your SSN though - could they push another number on top of it without your consent?

I didnt get any sort of check against the destination number.

[pgn]

The SSN is linked to your account, which in turn is associated with your number, @biscuits99 -

Answer to Can you keep your old cell phone number if you replace your SIM card? by Paul Crowley https://www.quora.com/Can-you-keep-your-old-cell-phone-number-if-you-replace-your-SIM-card/answer/Pa...

[biscuits99]

The SIM swap I performed was from 2 PAYG SIMs that were not related at all (my Dads and mine). My SIM was hours old at the time.

I was wondering if someone slips out your physical SIM and notes your SSN, could they wipe your number with a SIM swap - as I never saw a confirmation request sent to the destination SIM only the source.

I appreciate this was with Tesco Mobile, so maybe O2 works differently?

[madasaf1sh]

@biscuits99 

No as they need to know your MSIDN as well as the SSN.  And to do it just with SSN they would need to ring customer services, and have all your login details / access details to get into the Account.. 

Even enterprise customers who have blank sims, still need the MSISDN number and call the networks (this is across all of them) and get the network to do the sim change..

[Oxonian]

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@biscuits99 wrote:

My question is what happened to that number and the credit that was on the nano SIM?

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And to answer your question about the credit, I think you'll have to 'phone Tesco Mobile to deal with that. 

But my experience is that the customer service staff on Tesco Mobile are very efficient, so hopefully it will be resolved without difficulty. 👍

[biscuits99]

Thanks for the info. Glad there are more checks with O2.

Seems odd that Tesco Mobile let me do it with just knowing the destination PAYG SSN.

The Tesco mobile PAYG login just needs a phone number rather than a user/pass with the pay monthly: https://www.mytescomobile.com/