Nimbuzz, a Netherlands-based VoIP and messaging startup, is introducing a premium calling service called NimbuzzOut. This service is available via an upgrade of its mobile client, which is currently available from the iPhone’s iTunes Apps Store, the Ovi Store and GetJar. So far, Nimbuzz has offered a meta-client that works on PCs, Macs, Symbian, Android and the iPhone and allows you to sign into any IM service including Skype. NimbuzzOut is the first step toward revenue for the company, which has pulled in an undisclosed amount of funding from Mangrove Capital Partners, original backers of Skype. In addition to Skype, Truphone and Fring are two other competitors for this fast-growing service. Nimbuzz has been adding about 40,000 users a day, or about a million new registrations every month, and now has a total of over 10 million registered consumers. The company says nearly 30 percent of those registered are regular users.

Nimbuzz has certainly come a long way. At the time of its launch, almost three years ago, we were pretty critical of the VoIP-on-mobile service because it was a me-too offering that was quite a pain to use. A year-and-a-half later, Nimbuzz introduced a new meta client for the Symbian phones. It allowed you to sign into various IM clients. In addition, it allowed some basic VoIP calling, but it wasn’t really until they introduced the new iPhone client that Nimbuzz started to see some serious traction. My previous post gives a good overview of the Nimbuzz feature set.

The company just announced a super communication client for the iPhone that allows you to communicate in many different ways. For instance, you can make free calls over Wi-Fi to your IM buddies. You can also call folks on their landlines and mobile phones with SkypeOut using any one of Nimbuzz’s 10 VoIP partners including Gizmo5, Vyke, sipgate and A1 and, of course, Skype. This is a new feature in the service, and makes Skype In/Out Services more valuable.

These services also work over 3G and are described as “Nimbuzz Dial-Up VoIP” which essentially makes it possible to call others by dialing a local access number which then connects to anywhere in the world via Nimbuzz VoIP servers.

For the past month, I have been using the pre-release of NimbuzzOut on the iPhone to place calls to my far-flung group of friends and family. The calling prices are pretty good– about 8 cents a minute to India, 2 cents to the U.S., and 3 cents to the UK. If you look around, that is pretty much what you pay with most services — Skype is a bit more expensive.

The voice call quality is on par with Skype, which is still my communication method of choice for work-related calls. NimbuzzOut is dead simple to place calls: Just hit the call button, and you are good to go. You can, of course, use other calling services, but I don’t see any reason why considering Nimbuzz is offering good rates.

NimbuzzOut has a few features I personally like — you can natively use the phone client to buy additional minutes. I also like the fact that the client uses the native address book and doesn’t create a duplicate contact list. The Symbian client actually lets you edit, add and delete contacts from your address book.

There are a few things I don’t like: If you leave the notifications on, the client will run down your battery and leave the phone pretty useless. If you are using it on an iPhone, then you have to use the Wi-Fi connection, which makes me a tad upset because you can make Skype calls over 3G. You can make NimbuzzOut calls via 3G on Symbian phones, however.

Bottom line: If you are looking for a well-designed, easy-to-use, all-in-one messaging client that also makes cheap long-distance calls, then you don’t need to look any further than Nimbuzz. I have no qualms in recommending NimbuzzOut.

P.S. There is a reward for those who read the complete post. If you are among the first 50 people who send their name and Nimbuzz username to gigaom@nimbuzz.com, the company will give you a $25 NimbuzzOut credit.

Update: This offer is now closed. Thanks for participating.