Microsoft's Asia-Pacific chief, Chris Sorenson has slammed Apple's iPhone as 'irrelevant'.

"It's a great music phone, and I'm sure it will be fantastic and have an interesting user interface," Microsoft's Asia-Pacific head of smartphone strategy Chris Sorenson told press during a recent visit to Australia.

"However, it's a closed device that you cannot install applications on, and there's no support for Office documents. If you're an enterprise and want to roll out line of business applications, it's just not an option. Even using it as a heavy messaging device will be a challenge," the executive added.