To run ads with Skype there are now four ways:
1. Run through retargeting services such as Criteo, Adroll, Adnxs (and many others). Benefits: Running through these services can be geographic and other targeting options. Disadvantage: Not sure if the ads will appear on Skype.
2. Run through some DSP services. In theory, DSPs can also run ads for Skype if they have a service connection. Microsoft opens inventory on AdX for DSP buys. If any DSP has a connection with Microsoft AdX (MAX) it can be purchased, and inventory can be purchased on MSN, Skype, Outlook. Bid prices as purchased on AdX normally. Maybe the future will be. The benefits and disadvantages are similar to retargeting services.
3. It is now known that Ureka, Moore and MicroAd offer this service (purchased via parent company in Japan and resold). Should also be an option. Benefit: definitely appear on Skype. Disadvantage: price is high, budget must be high, the ability to target is limited in location.
4. Contact us directly with Microsoft (http://advertising.microsoft.com/en/skype).