I updated Monal after the 2.9.2 release to work again in the background. It appears that Apple has not just deprecated but removed the VOIP socket that Monal has used since iOS4 to run in the background. For the time being I am going to build with the iOS 9 SDK and things will continue to work. However the point where that is not a valid option will arrive at some time. When that does happen Monal for iOS will move to using an APNS notification and the XMPP push mechanism. Google talk will likely no longer work.