Skype has some bad news for you though their blog post appears to showcase it as something exciting.
The company said that they are adding advertisements to the Skype window when you make a one on one audio call.
These ads would only appear for users who are not subscribed to any paid service on Skype platform.
The company said:
While on a 1:1 audio call, users will see content that could spark additional topics of conversation that are relevant to Skype users and highlight unique and local brand experiences.
Skype had this for the interested advertisers:
Conversation ads are available for marketers to purchase in 55 markets where Skype is available. Users without Skype credit or subscriptions will see the ads during 1:1 Skype-to-Skype audio calls in Skype for Windows.
The company maintained that the ads would not hurt the quality of the calls. They would not feature any audio and they would also not expand to take more screen space.