Skype has barred third-party mobile VoIP provider Nimbuzz from offering its services, in what Nimbuzz claims is part of a new company policy ahead of Skype’s planned IPO. Nimbuzz says it has been instructed by Skype to remove support for all Skype services by the end of the month, effectively removing Skype from the Nimbuzz platform.

The move mirrors a spat earlier this year between Skype and Fring, another VoIP third-party aggregator, which also led to support for Skype services being discontinued. Fring had argued that Skype had simply blocked access, though Skype accused Fring of being in breach of its API terms.

Nimbuzz notes that the latest disconnect is “understood to be in line with Skype’s mandate to disconnect with all third party VoIP services ahead of its impending IPO.” However, Skype took the same line it had during the Fring dispute, accusing Nimbuzz of “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.” It added that it had offered to meet Nimbuzz to discuss the issue but has heard nothing back since early August.

Nimbuzz CEO Evert Jaap Lugt said that Skype’s decision to remove support for Nimbuzz was “unfair to its own and our users.” The firm said that, from 31 October, Skype users will be unable to chat, send messages or call friends and family on Nimbuzz and vice-versa. Nimbuzz will continue to provide support for a range of other VoIP and social networks on its platform, including Facebook, Yahoo, Windows Live Messenger (MSN), AIM, GoogleTalk Twitter, MySpace, ICQ, Gadu-Gadu and Hyves. Nimbuzz announced recently that it has surpassed 3.65 billion mobile voice minutes and 150 million downloads of its mobile app since launch in May 2008.

Meanwhile, Skype – which is available as an app on both the Apple and Android platforms – is looking to raise up to US$100 million via an IPO, but is struggling to turn many of its 560 million registered users into paying customers. According to a recent regulatory filing, only 8.1 million (6.5 percent) of Skype’s 124 million average monthly users were paying for premium services in Q2. It is also facing renewed competition from the likes of Google.