1 Background: What you need to know.
A. Extensions: You can run Skype under the same profile name on multiple computers concurrently. Inbound calls ring all clients whether in a call or not. Thus you can share the same line on multiple PC's even concurrently talking to different individuals. Example three PC's running in the office all with the same account name. One is actively engaged in a call.
B. SkypeOut: You can now dial multiple Skypeout numbers from the same PC, thus create a SkypeOut conference call with up to four people (I've not tried more). If you have an "extension" PC running as above you or another person can call a completely different group of people even while that first PC is engaged. Alternatively the second PC is available for a SkypeIn Call.
C. SkypeIn. SkypeIn is Skype's new service that allows you to secure "landline" PSTN style numbers for your Skype Account. This is currently limted to three per account. Thus if you purchase one SkypeIn number your PC will ring. Just like in A above if you are running the same client on more than one PC you can receive more than one SkypeIn call. Take the first call on the first PC from 14151234567 and then on the second PC (same SkypeIn number) take the second call from 1415 7654321.
D. Voice Mail: Voice mail picks up when there is no client available to take the call or the inbound call is sent / diverted to voice mail.

The tests and conclusions.
1. Running "my_name" on two PC's I dialed my 415 SkypeIn number first with my Vonage account. I answered on the first PC. Left it connected. Took my home phone, dialed my 415 SkypeIn number again. Answered that with the second PC. Left it connected. Thus at this point I had two different conversations going. I then tried dialing with my cellphone and I naturally got voice mail for the two instances were tied up in different calls. Voice mail was deliverd to both open clients.

2. I made the first SkypeOut call to a UK SkypeIn number which rang both his active PC's. I left that call connected I went to my second PC, and using SkypeOut dialed exactly the same UK SkypeIn number. Now there were to completely separate but in otherways Identical calls. Both were completely separate and private from each other. We then duplicated test one above. Note the billing implications of this. One SkypeOut account could provide lines out for many people.

3. I then made a SkypeOut call to Bill's UK SkypeIn number and then using Vonage dialed Bill's US SkypeIn number. For some reason it rang but didn't connect, sending me to voice mail. (Note will Bill's US number it failed, with his UK number it worked, with mine it worked etc. However not 100%)

4. Note when in one call and the second PC takes a call the ringing stops. If you were doing this is more than two PCs (eg the 50 example) you would want to turn off the ringers and create another "notification" approach for inbound calls. Eg the flashing red light. Call centers are managed by minutes and numbers served so there's an incentive to be the first to pick it up. Like playing Snap.

5. In the Skype config XML file (in the hidden applications folder) there is a line that allows multiple inbound calls. Thus this suggests that this is either a feature or something that Skype may try to control or enable control over in the future. There are some elements that also need additional work. For example where an account is associated with more than one SkypeIn line. How do you know which one is being called. The account may provide the context.

Skype Strategy:
We would suggest Skype maintain the "as many "calls" concurrently as you have multiple clients open and cap it between 3 and 5. Skype architecture is clear the "extensions" concept is embedded in the design.

We believe that Skype could offer a 1-800 number and then offer the equivalent of mulitple lines by simply applying a setting in the accounts system. Thus you could buy a 50 line-in package. This would eliminate traditional rollover. Skype could do this "dirt" cheap. Say $5 per year for each extra extension.

The big element missing from the above is the capability to associate more than one account name with the open Skype client. For example In the call center we want to load up the buddy list with the 50 operators names taking calls. From the one client any of the operators should be able to text or conference in one of the other operators. This needs to be possible without running a second client (although easy to do) on everyone's PC. Perhaps the solution will come in "internal" call forwarding.

Skype call forwarding will be very important. While many of us want it already to forward our SkypeIn line to our mobile phone, the capability to hand off a call to someone else logged into the same client requires each client to be able to poll for others like it and then redirect to the correct extension. This thought could be extended and is very important to the enterprise or small business. What we are talking about is probably a modified "supernode".

The Skype API provides many opportunities in this area from statistics to call management and notification. Similarly it can be used to drive page support dependent on number called or customer details etc. All in all don't underestimate the power of what's feasible now above.

Call Center Implications:
Hardware?: Skype could radically reduce cost and complexity at the backend. Is only one number really necessary? What happened to "mulitple" lines required? Should you think about it as a "call center"?
Organization and Structure: What does a decentralised P2P call center look like. Rather than the scenario above what happens when you Skype enable a distributed call center. Each worker has their own PC, a broadband connection Skype and an API plug-in that provides reporting and random recording for quality control. The cost of this equipment setup is zero.

Time to Test!
Test multi-PC's. We are particularly interested to hear from those that are willing to test 10 or more PC's in a concept test. We will help you set it up running two SKype clients concurrently on each machine.
We don't have confirmation from Skype that what we've learned we can do today is either a feature (they weren't planning to make noise about yet) or a bug. We certainly hope that it is not the latter.
We would be happy to discuss further with call center operators.

In conclusion we believe there are some simple strategies emerging for powering up a small enterprise using Skype and a well crafted SkypeAPI plugin manager that can direct calls and enable appropriate support.