In a huge move for VoIP and mobile fans all over, AT&T has made it public that they will allow Internet telephony applications to be used over their 3G cellular network.

Skype, the granddaddy of consumer VoIP products, has been lobbying the FCC for many moons now to get AT&T to open up 3G bands for Skype usage. In a blog post, CEO Josh Silverman praised AT&T’s announcement.

What does this mean? If you have Skype running on your iPhone via AT&T, you’ll soon be able to make Skype phone calls over the cellular network. This was possible before, but only via Wi-Fi and not a 3G connection.

Om Malik praises increased telco competition for today’s AT&T announcement. Some are saying AT&T is trying to counter Verizon Wireless’ announcement that Google Voice will be support on Verizon’s new Android based handsets, due in the coming weeks.

Either way, being able to use Skype via 3G on AT&T is a huge bonus for people who make international phone calls or are otherwise using Skype on their mobiles. Thank goodness for competitive energy!

For those interest, here’s the official announcement from AT&T.