This week, the Global mobile Suppliers Association (GSA) announced 100 mobile carriers are now offering HD voice service around the globe. In addition, Sprint says it will offer its version of HD voice nationwide by this summer. Add in NTT DoCoMo's LTE roaming announcement and a lot of pieces are falling into place around the globe with the latest group of carriers offering HD voice providing some interesting data.

In the first three months of 2014, eight operators turned up HD voice. Worldwide, HD voice is available in 71 countries, with 22 countries having at least two mobile HD voice operators. Of the HD voice 100, 89 carriers are 3G/HSPA-only operators. Six operate both 2G GSM and HSPA networks. There are two GSM-only operators and 3 LTE operators using Voice over LTE (VoLTE).

If 100 operators sounds like a lot, there's still a long way to go. GSA President Alan Hadden says around 1 in 5 HSPA operators offer HD voice service, but market momentum is "positive" and "growing" for mobile HD voice service. 

HD voice capable handsets aren't the issue. GSA lists 329 HD voice phones -- more than double the number of a year ago -- have been announced by 19 manufacturers. In its announcement this month, Swedish carrier Tele 2 points out that most mobile handsets sold since 2012 already support HD voice.

Sprint is getting a lot of hype this week from its announcement it will make HD voice available nationwide by the first of July. Of course, the carrier has been selling HD voice phones since the spring of 2012 and making promises about limited rollouts by the end of 2012, which spread into 2013 and finally started turning up a limited number of cities starting in late 2013. If you don't believe me, do a Google search on "sprint HD voice 2013" and look at the number of stories that pop up.

(Yes, I'm not a big Sprint fan these days. Having been burned on WiMAX, its HD voice representations are déjà vu all over again. And we haven't even discussed how Sprint's 1X Advanced HD voice technology is different from everyone else's in the U.S. marketplace. Or the great mystery if Apple 's iPhones will support 1X Advanced for HD voice. Or why the telecom media at large has given Sprint a big pass).

Buried within this week's GSA announcement was a short reference to interoperability: "Interconnection between competing networks for end-to-end HD voice calling, as well as international roaming for HD calls, are priorities for 2014."

Interconnection is happening in the background, but carriers aren't talking a lot about it. For example,  just today NTT DoCoMo announced its LTE customers will be able to roam outside of Japan starting next week. Deals have been struck with AT&T, Rogers, Hutchinson and Bouygues Telecom, enabling LTE roaming to the U.S., Canada, France, and Hong Kong, with Malaysia to be added in April.

LTE traffic roaming is enabled through what carriers call IPX (IP eXchange) services. HD voice calls can (and are) moved between carriers using IPX, so there aren't any technical obstacles to making HD voice calls between different carriers -- only business arrangements.