configurable - Phone locking with SIM[s]

Question

Usually Iphones etc are locked with some operator e.g. AT&T etc which then onwards cannot be used with others unless these gets unlocked with s/w upgrade etc.

My question is about making this locking configurable with a SIM[s] and not with an operator. This is to address the phone thefts etc. This way the users can lock the phone with a particular SIM. This locking can be removed later by users themselves. This may also need the operators/phone manufacturers support based on the mechanism. Here any s/w only mechanism may be forcefully overridden upon the wholesale reformat hence some device level support may be needed.

I am not sure if this mechanism already exists.

Answer 1

More theft more new phone will be sold, so it is not in operator or phone vendor interest.

Answer 2

In order to prevent thefts there are network level methods implemented in the GSM standard. That works in the following way, every time a phone is connects to a GSM network it sends the GSM carrier its IMEI. The carrier can then decide to refuse to offer GSM service to that specific device because the IMEI has been black listed as belonging to a stolen device. It's as simple as that. Subsequent factory resets or flashes of new firmware will not change the device IMEI so the method is safe from most device tinkering. I'm saying most, because it is possible to change the IMEI on a device, but that is extremely difficult.
In US ATT, Verizon and T-Mobile have agreed on using a shared IMEI black list database. In Australia and UK IMEI black list databases have been in use for a few years now.
To conclude, the best idea is probably to report your device's IMEI to your operator as it is by far the most effective method. Having a software solution like you suggest can help, but because it's easier to circumvent, it is going to be less effective. Furthermore a network level solution will have an easier time reaching public understanding and the 'no setup' part of it makes it more desirable.