Add T-Mobile to the list of carriers offering underground cellular service to riders of the Chicago Transit Authority. The CTA signed a 10-year contract with T-Mobile that is expected to generate at least $3.1 million. T-Mobile is the fifth operator to lease the CTA's subway network. The others offering service include Cricket Communications, Verizon Wireless and U.S. Cellular. AT&T signed a contract with the CTA in June and service is expected to launch later this year. CTA is also in talks with Apple over a $4 million deal to spruce up the North/Clybourn station on the Red Line, with the company getting first dibs on advertising and possibly first refusal of naming rights.