Comprehensive reporting on the state of cell operators merging services with Wi-Fi: What's coming? Combined Wi-Fi/cell handsets, combined services, combined billing. T-Mobile will offer its voice customers hot spot service on the same bill. Seamless handoff between networks is also on many people's agendas, but they're concerned about making sure customers are aware of the cost change. And, Wi-Fi is the gap-filling technology for cell operators as they gear up to faster cell speeds.