Disable Skype ads: 1.) Add hosts to your hosts file 2.) Flush DNS resolver cache (ipconfig /flushdns)

hosts

# Block Skype ads
127.0.0.1 *.msads.net
127.0.0.1 *.msecn.net
127.0.0.1 *.rad.msn.com
127.0.0.1 a.ads2.msads.net
127.0.0.1 ac3.msn.com
127.0.0.1 ad.doubleclick.net
127.0.0.1 adnexus.net
127.0.0.1 adnxs.com
127.0.0.1 ads1.msn.com
127.0.0.1 ads2.msads.net
127.0.0.1 aka-cdn-ns.adtech.de
# Keep "apps.skype.com" if you want to see Skype Home (prepend # at line below)!
127.0.0.1 apps.skype.com
127.0.0.1 b.ads2.msads.net
127.0.0.1 bs.serving-sys.com
127.0.0.1 cdn.atdmt.com
127.0.0.1 cds26.ams9.msecn.net
127.0.0.1 db3aqu.atdmt.com
127.0.0.1 ec.atdmt.com
127.0.0.1 flex.msn.com
127.0.0.1 g.msn.com
127.0.0.1 live.rads.msn.com
127.0.0.1 msntest.serving-sys.com
127.0.0.1 rad.msn.com
127.0.0.1 sO.2mdn.net
127.0.0.1 secure.flashtalking.com
127.0.0.1 static.2mdn.net
127.0.0.1 static.2mdn.net

# PRO-TIP: Removing the adds does NOT remove the add placeholder side bar(s)! 
# This can be removed by going to: %appdata%/skype/YOUR_USER_NAME/config.xml 
# and set all Advert-related values to 0:
#
#    <AdvertEastRailsEnabled>0</AdvertEastRailsEnabled>
#    <AdvertLargeEastRailCutoff>0</AdvertLargeEastRailCutoff>
#    <AdvertNorthRailCutoff>0</AdvertNorthRailCutoff>
#    <AdvertPlaceholder>0</AdvertPlaceholder>
#    <AdvertSmallEastRailCutoff>0</AdvertSmallEastRailCutoff>

This no longer works as of today - I'm getting ads with all of these host edits. Did MS add new ad sources?

Just block "apps.skype.com". I don't need Skype Home.

Blocking apps.skype.com seems to block every ads. The problem is that this domain also provides the Skype Home. I'm going to investigate in order to find new ad domains. But for the moment, we'll either have to face the ads or to remove the Skype Home.
EDIT: after like an hour of investigation, I found out that AdNexus was using many subdomains, and I also found out that wildcards such as * do not work in hosts files.
There is nothing more we can do. Either find a software that allows wildcards (eg blacklist *.adnexus.net), or use PeerBlock with the "Ads" subscription list.

Keep "apps.skype.com" if you want to see Skype Home !
This line is useless. Without, Skype is ad-free !!!

Thank you @eyecatchup !
 

Thank you! It worked. And cz*76, thx for the tip.

I've add some urls in my fork: https://gist.github.com/joielechong/d0042338fd3132013aec4ee56045e558

👍 for "apps.skype.com"

using only 127.0.0.1 apps.skype.com is enough to blocks all ads (but deactivate the skype home panel as well as a benign side-effect)

Hi!
Recently my Skype has stopped working after I've used hosts file to block ads. The problem is that my hosts file is custom: it includes many sources... So it's hard to find which one made Skype unusable. Any ideas where to find hosts I should whitelist to unblock Skype?