I saw somewhere - it's not like "I know a friend" but literally read somewhere - IMEI is just configurable with standard cracked virus-loaded copies of QXDM :p

But realistically, none of that matters. You'll be the only one in 10 miles with this SIM that always uses an never-before-seen IMEI that connects to the exact same set of domains. That's some mall ninja stuff.

Carriers don't just log IMEI/IMSI, as well as last hop cell towers and your precise location, they need those information to route packets back to the phone. You can't establish TLS with bogus IP addresses. That's why people like Stallman or unnamed friend of a friend ex-CIA guys on Internet says cell technologies are evil mass surveillance tools.