SIM Reliability and Maintenance

WOTSWOT

I bought my only mobile in 2011 it is a 2g Samsung GTE1080i, from Tesco. I think I paid just £12 for it and am still on their PAYG lite tariff, which is still the same rate as it was then.

I only use it for emergencies and OTPs. It has been extremely reliable and all I have needed so far is a new battery when my talk time dropped down to just a few minutes.
But last week it froze up on me and the only way I managed to fix it was to visit my local Tesco mobile phone shop where they fiddled with it and got it working again. They didn't say what they had done but just said the problem was probably due to a bad contact on the SIM. I don't recall ever touching the SIM at all during the 14 years of using it.

I became very suspicious and thought this might be some ploy they had used to reset my SIM into some strange fault state and so force me to upgrade to a new 4g.

However I have since researched SIMs and found my SIM to be well over it's expected lifetime and also learnt that I should have maintained it by regular cleaning. Also it is possible that I might have had contact corrosion due to long term humidity.

In retrospect perhaps Tesco were right and it is pure coincidence that my phone failed just as 2g is being wound down.

How important is this maintenance, do  other here do it or have SIM reliability issues?

Ayr_Rage

If your SIM is in a slot that doesn't have a gasket preventing moisture and dirt ingress then what happened to you is not at all surprising.

Also surprised that Tesco haven't asked you to update the SIM in all that time, if they do there is nothing suspicious happening, it just means the replacement will work in all modern handsets.

fwor

If your SIM is old enough to have gold-plating on the contacts, there's really not a lot of "maintenance" you can do other than to wipe off any dust that might have crept in over the years.

More recent SIMs seem to have moved to a cheaper contact plating which is a bit more prone to corrosion/tarnish, but that should be easy enough to polish away with some coarse cloth or kitchen towel.

The unfortunate thing about them is that the underlying material is typically only just rigid enough for the job, and on some phones the contract pressure is high enough to dent it, leading to poorer contact in the dents. There's not much you can do about it if that happens, other than to get a replacement SIM (or change contract and transfer your number across).

Frozen_up_north

A 14 year old SIM could need replacing, nothing unusual in that as networks can make security and compatibility alterations that require an updated SIM.
Pop into a Tesco store and ask them to update the SIM.

vacheron

It did seem a little paranoid that you walked into a Tesco mobile shop on your own accord, they fixed your phone and you left with it fully working again, yet you still thought there may have been some underhanded ploy at work?

As you have since researched, many contacts (such as plugs and sockets around your home) rely on occasional plugging and unplugging to wipe their electrical contact points clean and provide a fresh contact . 

A SIM that has been sitting in a phone for 14 years without being moved could very possibly oxidise. If this caused an open circuit connection on any one of the 6 power / signal pads of a standard SIM, this would render the entire SIM inoperable.

In order to prevent this, you can just slide the SIM in and out of its holder once or twice a year, alternatively, you can remove the SIM and gently wipe the gold contacts with a pencil eraser (the "pen" side of one of those two tone erasers is even better). This will visibly remove any tarnish and brighten up the contact pads. You can do the same with the battery contacts as well (providing your eraser is non-conductive)!   

finbaar

vacheron said:

It did seem a little paranoid that you walked into a Tesco mobile shop on your own accord, they fixed your phone and you left with it fully working again, yet you still thought there may have been some underhanded ploy at work?

As you have since researched, many contacts (such as plugs and sockets around your home) rely on occasional plugging and unplugging to wipe their electrical contact points clean and provide a fresh contact . 

A SIM that has been sitting in a phone for 14 years without being moved could very possibly oxidise. If this caused an open circuit connection on any one of the 6 power / signal pads of a standard SIM, this would render the entire SIM inoperable.

In order to prevent this, you can just slide the SIM in and out of its holder once or twice a year, alternatively, you can remove the SIM and gently wipe the gold contacts with a pencil eraser (the "pen" side of one of those two tone erasers is even better). This will visibly remove any tarnish and brighten up the contact pads. You can do the same with the battery contacts as well (providing your eraser is non-conductive)!   

Very much this. The worrying about scams come from not understanding how things work and that actually makes people more prone to being scammed. The OP will need a new phone relatively soon but if they the 13 year old 4g is new then they had better ask for advice before buying anything.