Starting fresh on the network, which Sprint is building with Ericsson, allowed it to build in support for future technologies, Azzi said. For example, the network architecture is ready to accommodate small cells that can help to make more efficient use of spectrum. Sprint already has more than 600,000 femtocells in use now. It plans to start installing picocells in large indoor venues such as stadiums and airports late this year and in early 2013, with picocells to cover outdoor public areas possible later next year.
The core of the network can also accommodate Wi-Fi, Sprint said. The company has no current plans to deploy Wi-Fi itself, but third-party public hotspots can help give subscribers capacity.
The Network Vision technology is fully tested and ready to go without surprises, said Iyad Tarazi, vice president of network development and engineering. Sprint's thorough development process took effort: Engineers had to do 75 releases of software and 23,000 test cases, Tarazi said.
One-third of Sprint's radios for its narrowband iDEN service are on track to be shut down before the end of this year. Sprint is working at shifting over iDEN users to its 3G CDMA network and said it is happy with progress on that score. The popular push-to-talk feature of iDEN is being replaced by Direct Connect, which runs on 3G and now matches the original technology in call setup, latency and call success, according to Sprint. The company is also making Direct Connect available as software for integration into third-party applications.
Sprint's other legacy network, the WiMax service it wholesales from Clearwire, can remain part of its offerings through 2015 or later. WiMax became available on Sprint's prepaid Boost and Virgin Mobile services this week.