Is there a way to check if a phone is stolen using an IMEI number?
There is indeed, the best commercial version that we use at loveit coverit is: https://www.mobicode.co.uk/check/
For a free option, with less features you can use: https://www.imei.info/
(We are not affiliated and do not endorse either of these websites)
When a phone is stolen or lost we require it to be reported to the phone supplier for blacklisting, they do this using the IMEI number. This means the phone can not be used, resold, or otherwise involved in criminal activity. This not only protects you and your device, but also ensures claims made are legitimate.