I've got mobile phone insurance through my bank as part of my current account. When claiming, they would need a 'proof of usage' document which simply states that your phones IMEI number had been used to make calls on the account. Tmobile said to be that they do not provide this for SOLO (sim only) customers. so if your insurance is through a 3rd party, you WILL NOT be able to make a claim.

I spoke to someone at o2 who said that it would not be a problem to provide this 'proof of usage', and he kindly emailed me stating that they will provide this document for all their customers, even sim-only ones.