Identify "Catch" User Sending Harassing SMS Messages

Facts: 1. Client is receiving multiple texts every day with threats from "spammer." 2. "Spammer" is using multiple VOIP numbers through Envoy and Level 3 (Sourced to Neutral Tandem IL LLC). 3. Spammer responds to messages sent back to the VOIP numbers 4. Strategy to catch this spammer must include interaction through SMS or MMS or a link to a website Goal: 1. Identify the Spammer (As much information as possible. User Agent, Device, IP, Mac Address, Geolocation, Real Name, Address, etc.) Project: 1. Develop a strategy to catch and gather user's information (ie bait user to "like trap" webpage or use an MMS strategy I don't know about yet) 2. How will you solve the problem of the user on a mobile device with geoservices turned off? Give me your thoughts and your quote. I would like to get rolling ASAP. You will be hired for future Skip Tracing services for our International Legal Services Firm.