BusinessWeek has the skoop. Mobile carrier 3 will offer a Skype branded mobile with the iSkoot app this month. iSkoot confirms a Skype phone will be launched, and iSkoot will be on it. BW puts first ship in the next two to three weeks.

This is an enormous opportunity to extend the Skype brand in in the UK, Italy, Hong Kong, Australia and Hutchison Whampoa's other markets. Unlike apps you download to your phone, or even releases that come preloaded with an icon in the main menu, a "Skype" phone should put the Skype experience front and center.

iSkoot's technical architecture makes this possible. But it's only half-VoIP.

The problems: Skype tried to create complete versions of the Skype client for mobiles. The code Skype came up with burned through data plans, burdened underpowered data networks, and overtaxed most mobile CPUs.

iSkoot gets around these barriers with some clever engineering.

1. iSkoot wrote their own client. This lets them keep it lightweight.

   • The client offers a minimal subset of the Skype for Windows client's features.

     • It starts with a few account services: activate a new skype user, log in, log out, add SkypeOut service and credits.

     • You can see your Skype contact list, add or remove buddies, see their presence, change your own presence.

     • You can Skype chat with emoticons, conference chat, call Skype friends, call SkypeOut numbers and answer Skype calls.

     • A unique feature for iSkoot: templates for quick answers in Skype chats.

   • Downside 1: Things you cannot do with this generation of iSkoot client: anchor a conference call, transfer a call, transfer files, make or answer Skype video calls, participate in Skypecasts. UI only localized for eight languages.

   • Downside 2: No Skype plug-in API for the iSkoot client.

2. The iSkoot client talks to iSkoot servers, not the Skype network. The servers do that for the client.

   • This avoids trying to map Skype's whole p2p architecture over a mobile network.

   • It also lets iSkoot co-locate their servers in a wireless carrier's data center, for better security and uptime.

3. the iSkoot client puts voice calls over the carrier's voice network, unlike Skype.

   • Carriers love this: your Skype calls show up as billable minutes.

   • Your Skype voice call and your regular phone call both travel over the same network until they get to your carrier's switch. The carrier routes your Skype calls to the iSkoot server. The iSkoot server runs a PBX switch which answers the call and bridges them to the Skype network. 

   • Downside 3: iSkoot voice calls are not encrypted on the mobile leg of the call.

   • Downside 4: Audio quality is lower than Skype's standard wideband because the iSkoot client is using a phone's ordinary codecs and microphones. Mobile users may not notice this difference. 

4. the iSkoot client puts all Skype's non-voice traffic over the data network. IM, presence, authentication, etc. This is only a trickle of data, compared to voice or video, so there's little to no stress on a carrier's network. Again, networks love this.

   • Downside 5: Because Skype hasn't shared their encryption algorithms with iSkoot, your Skype chats aren't encrypted, although your login is.

5. iSkoot servers run huge banks of Skype VoIP clients with management software. These servers connect iSkooters to Skype. 

   • The iSkoot server runs a software PBX/switch that answers your phone call and bridges it to a Skype client. The Skype client running in iSkoot's server farm thinks your mobile phone looks like a PC headset, with audio in and out.

   • iSkoot servers talk to the Skype.com server for authentication, logging in to the Skype network as a user.

   • iSkoot servers talk to the Skype cloud for chats, presence, and other operations (made possible by Skype's client APIs).

   • iSkoot servers talk to Skype's gateway services, SkypeIn and SkypeOut

Who benefits?

• iSkoot makes its money by revenue sharing from mobile carriers, at least for now.

• Carriers sell more data plans but use them only a little more, and increase billable minute sales, without promoting scary Wi-Fi. These are

• Skype shows up in more people's lives more of the time, without rebuilding for Symbian 60, Blackberry, Windows Mobile, UIQ, Palm, or J2ME platforms.

• Skypers get the 90% of the essential Skype experience: contact lists for dialing, time savings of presence 1.0, collaboration in group chats.

• Handset device makers, like Sony Ericsson and Nokia, can offer new flavors of 

What's ahead? Informed speculation: