My router assigns an internal IP address to my phone, based on the MAC...just like any other WiFi radio. That MAC shouldn't leave the local network. Wifi shouldn't have anything to do with the IMEI other than a MAC will identify the vendor, and the IMEI will indicate the vendor as well (I think?). Since you can't easily (if at all?) spoof a phone MAC, your real one would show up in Starbuck's router logs, etc... There may be some correlation available by taking all IMEI's connected to a tower, and then getting the router logs of all open access points within tower range and looking up the MAC vendor ID and trying to match them to what model the IMEI is...but I don't know...seems very difficult and I'm not a 'mobile guy'.
PD
Edit: There is also the IMSI, which identifies "you" it looks like.
https://en.wikipedia.org/wiki/Intern...pment_Identity