Phone keeps saying either no sim or invalid sim, Help!!

[caithnesschick newcomer]

I have an iPhone 3GS which I've never had a problem with until yesterday when I changed to GiffGaff! I put my GiffGaff sim in and switched it on and it was fine, I could use it straight away (this was in the morning) by the evening my phone was saying invalid sim, I switched my phone off and on again and all was well. Today has been a disaster!! Woke up to phone saying no sim, after switching on & off my phone wouldn't let me unlock it then it went black and then the apple symbol appeared??? This has been happening all day??? Please can anyone help me solve this problem otherwise I think I'll need to go to a proper provider

[rushtonwolves pioneer]

re-sync the phone with your itunes account to get it working

[sneaky007 augur]

Hi Caithness,

It sounds like an faulty sim you can either order a replacement sim or carry out a sim swap

If you wish to get a replacement sim please follow the link below
http://giffgaff.com/support/lost

Note for security the current SIM will be immediately disabled and replacement sim is barred on delivery for security purposes. You will need to contact an agent to get the bar lifted . replacements don't require any topping up. during re-activation the replacement sim there will be a slight interruption in service whilst re-activating the replacement sim

or if you have a spare giffgaff sim laying around you can carry out a sim swap See here for how SIM swap works - http://is.gd/ggsimswap

[dalan giffgaff pensioner]

Hi.
You need to try your sim in another phone, to rule out a faulty sim or phone.

[grandmaeileen graduate]

Hi is your phone jailbroken?

If so try switching to 05.13.04. Seems to be a more stable baseband.

Also it could be your sim holder or when points that touch the sim inside your phone need tightening up.

The dreaded no sim or signal drop out is baseband linked though.

[kaleem7877 cicerone]

Your sim might be faulty

[bruno00 grand master]

it is nothing to do with sim card. It is your phones fault. Take to the phone shop. They may be able to help you.

[caithnesschick newcomer]

No it's not my phone as its been perfectly well until I put the GiffGaff sim in it!

[caithnesschick newcomer]

Not sure it was unlocked by O2 6 months ago and worked perfectly well with my old Orange sim :-(

[bruno00 grand master]

are you able to use different sim card in your phone?