A year in review wouldn't be complete without a hat-tip to the Mobile VoIP space. One of the most popular features FierceVoIP ran this year was "Ten Mobile VoIP Apps for the iPhone" which had a lot of readers chiming in on their favorite apps as well. If remember this time last year we thought that mobile VoIP was getting serious, but back then you still couldn't make a 3G VoIP call over the iPhone. With the rise of the smartphone and the easy access to the mobile Internet, the world of Mobile VoIP has expanded by leaps and bounds in 2010.

To start, we saw a number of VoIP apps launch on Android and iPhone ecosystems--some over WiFi and then others over 3G. After a long wait, Apple approved VoIP apps to make calls over 3G--just a few weeks after our roundup last year. iCall was the first service to get a 3G VoIP app onto users handsets with it's app description page in the App Store expressing the excitement of many mobile VoIP enthusiasts: "3G 3G 3G 3G! You can now use iCall over 3G networks!!!" From there the flood gates for true 3G VoIP apps that no longer relied on WiFi to make calls were opened. Almost immediately, RoamAnywhere announced an enterprise-level secure VoIP service for the iPhone. In May, Skype 3G went live. In April, Apple announce that the new version of the iOS would allow apps to run in the background--making the 3G VoIP apps much more useful.

A number of the iPhone apps have had similar launches on the Android system. Skype took until October to get on Android and without a hack it only worked over WiFi. Other apps have hit the Android system including Viber, Counterpath, Nimbuzz (with HD). Fring, meanwhile, has announced that it has been making a killing with its VoIP app on Android. Fring was one of the first companies to allow users to make mobile video calls over 3G and WiFi to other fring users. The company claims that they are pulling in $10,000 in revenues daily just from Android phones and are on course to double their revenues in 2011.

Frost & Sullivan sees a bright future where mobile VoIP will generate $29.57 billion by 2015.