|Windows Phone 7.5 introduced the ability to|
use different messaging services in one
Most impressively the way that the default messaging client handled all communications within its slick, totally native design. The seamless ability to switch from one messaging platform to another within the same conversation without any inconvenience was a world away from what was available on iOS and Android.
Introduced in Windows Phone 7.5 it allowed you to continue a conversation whilst jumping between text message, Windows Live Messenger and Facebook Messenger.
It was a unique selling point and now it's gone.
Skype replaced Windows Live Messenger, now Facebook has killed access to its messaging platform outside of its Messenger application,
Messaging on WP8.1 is now the same tired, jump from app to app paradigm as everywhere else, and that's a shame.