Rotterdam, Netherlands-based Nimbuzz was asked by Skype to remove support for Skype services, effective October 31st. Actually, it’s not just Nimbuzz — Skype is disconnecting all third party VoIP in preparation for an IPO.

In a statement, Skype said that Nimbuzz is  “using Skype’s software in ways which it was not designed for, in a breach of our API Terms of Use and End User Licence Agreement”.

Another instant messenger service, Fring, which temporarily blocked Skype for overload reasons was denied by Skype to reconnect following its introduction of Skype video chat.

Nimbuzz mobile app allows user to access their instant messengers including MSN, ICQ, Google Talk and more in a single application. With 30 million users, it has a total of 3.5 billion mobile VoIP minutes in 2009. While Skype blocked Nimbuzz, VoIP to other Nimbuzz users is still possible, and other Nimbuzz services is still readily available.

Rumors have it that Cisco will tender for Skype ahead of the IPO, though this has yet to be confirmed.  Skype is riding a big wave as support for its services regains interest in the company.  It’s striving towards an IPO, while also focusing on a number of feature releases, many of which involve direct integration with third party sites and services like Facebook to achieve global growth.  This has been the reason behind Skype’s latest requests to block certain services, claiming they violate the VoIP tool’s terms.

It’s a move that will get several third parties in line with whatever Skype is doing, the way they want it to be done.  As Skype looks to become a major leader in the telephony revolution, it’s important for the company to maintain a dominate position and have control over the use of its applications.  These things always tend to become a different story when investor interests are involved.

In other IPO news, Mail.ru inches closer to its offering, declaring a $5.7 billion valuation this morning.