Microsoft will block VoIP applications - and those that change a device’s default browser - from being sold in its new app store.
The company has released its list of 12 prohibited types of application, which also includes apps larger than 10MB and those which enable payment outside the online store, called Windows Marketplace for Mobile.
The ban on VoIP applications applies to those which use a mobile operator network, the list states, meaning apps which utilize WiFi may be acceptable.
Microsoft has also moved to protect operators by barring any app advertising or linking to mobile voice plans, and those which change a device’s default dialer or SMS/MMS service
To protect Microsoft's own interests, apps promoting or linking to alternative marketplaces will also be blocked, as will apps that change a device's default search client or media player.
The publication of the list of banned apps is in contrast to the approach by Apple, who has never revealed the terms and conditions of its apps store and who has come under fire both for the apps it has cleared for sale and the apps it has blocked.