As 2013 comes to a close, only a few small U.S. carriers have deployed Voice over LTE (VoLTE) as a commercial service. Both AT&T and Verizon hinted at and spoke of various time frames for VoLTE deployments, but neither carrier has launched service yet. AT&T still has until the end of the year before its latest public pronouncements expire, but it seems unlikely the carrier would make a big promotional push of a brand new service in the middle of the holiday season.

Worldwide, there are 244 commercially launched (i.e. collecting money) LTE networks in 92 countries, according to the December 5, 2013 market summary report just issued by the Global Mobile Suppliers Association. 

Only a handful have deployed VoLTE, with the most significant launch occurring in South Korea in 2012, with LG, SK, and KT all offering the service. Azercell in Azerbaijan and O2 Germany can be added to the short list, along with Evolve Broadband serving 13 counties in Texas. It should be noted Evolve is offering Android tablets for its VoLTE offering, so it isn't clear if this a "true handset" type of service wired into IMS or an over-the-top soft client experience with no quality of service (QoS).

AT&T was expected to turn up VoLTE by the end of 2013, according to press reports starting from January through the middle of the year. By October, the tune being fed to the media was AT&T "might" launch its first VoLTE-capable handset this year -- whatever "VoLTE-compliant" is defined as this week.  VoLTE service is now expected to appear in 2014.

Verizon's track record in waiving the VoLTE promise dates back a couple of years at this point. Way back at Mobile World Congress 2011, Verizon Wireless said it would be introducing VoLTE in late 2012. By early 2012, reports had slipped back deployment to early 2013. And by late 2012, the date had moved "to the right" to 2014.

More recently, Verizon indicated it might offer a VoLTE-compatible handset (again, what does that mean, precisely) for the 2013 holiday shopping season. Service is still expected to be turned up in 2014, but the delays put the carrier in a race with AT&T for bragging rights of network and technical superiority.

Sprint and T-Mobile may or may not deploy VoLTE next year. Sprint's various tribulations in rolling out HD voice as a part of its Qualcomm 1X Advanced CDMA upgrades -- a year-long saga -- make me skeptical of reports indicating it will have VoLTE out in 2014. T-Mobile is, well, T-Mobile and it is happy to wreak havoc with the status quo, so I suspect it may be working on a surprise or two when it finally deploys VoLTE.