Skype for SIP Beta, Connect SIP Infrastructure To The Skype Community

(Skype has Approved Shoretel Gear to be compatible with Skype for SIP, with this Shoretel becomes the first IP PBX vendor to be approved by Skype.)

Skype for SIP.
Skype has announced Skype for SIP. a service to connect SIP comminications devices to Skype netwoek allowing to call any landline or mobile phones with low Skype rates. It also allows millions of Skype users to call you directly, for free.
One could also put Skype for SIP to work in many a ways like;

• With click-to-call buttons customers can contact you directly from your site or email.
• Customers can call you on a local online number.
• Your business will have a presence within the community of over 440 million registered Skype users.
• Free Skype calls to the office when travelling.
• Business as usual for home workers – the office is one click away.
• Your business will be globally accessible and visible to the Skype community and potential partners.
• Improve long distance business relationships with free inbound calling. 

 All for rates from just 1.7€¢ / 2.1US¢ per minute (A connection fee applies.) to more than 35 countries worldwide.
For technically minded,  Skype for SIP is a standards-based RFC3261 SIP interface.

• Signaling: SIP (rfc3261)
• Channels: Maximum of 300 channels (concurrent calls)
• Authentication: IP authentication or SIP DIGEST
• Transport: UDP, Support for Far end NAT traversal
• CODECS:G.711 µLaw/ALaw (20ms/40ms), G.729 (Annex A and B)
• DTMF: RFC2833 and SIP INFO
• Call Support: Call on Hold, Music on Hold, Call transfer, Early media
• Number Format: e.164 (country code and national number)

and all you need is a SIP-enabled PBX which supports either of the G.729/G.711 codecs.

You can Apply for Skype FOr SIP here.