Thanks Gualtier - very well explained and appreciate each point described by you. Yeah i am aware about the scanning interval and efficiency while it goes to background. My requirement is like to send Push Notification 2 per hour to individual device and not more than that to single device. Also my both app will connect at-least once to each-other and then it will goes to background/suspended state. So when i will keep both them in background and move out of range then get back, they are connecting and exchanging data. When app receive notification, i am initialising CentralManager and PeripheralManager, At CentralManager, willRestoreState called with Peripheral as connected. And after sometime get callback for didModifyServices as i am initialising Peripheral-manager. But when i got connected peripheral from WilrestoreState, and try to discover services, it doesn't contain the service i had added while advertising. Could you please guide me where i am missing the trick.