Incorporating a VoIP in my site

[Matrixster]

I have a community site and I want to incorporate a VoIP to allow users to "call" each other.

Should I build my own VoIP or should I use an already created service such as
s k y p e

What are some issues I should consider here?
What would be convienient for my users?
Is it that difficult to create and operate my own community voIP?

[txbakers]

I would go with Skype - why reinvent the wheel?

[Matrixster]

>why re-invent the wheel...

Well hey, popular voIP's have been bought up alot lately for a good chunk of change, and if my community site gets huge, I would have all that user base and could sell it as well.

Just a thought....