[Linphone-developers] ios Chat notification

[ios developer]

Hi, 
i have my own sip server on which i have integrated the notification for call and chat , for chat server sending the call-id in the payload , but the linphone method linphone_core_get_new_message_from_callid was unable to get the message detail from this call id and it return nil.
in the linphone document they said that when app is in background , stop the core linphone and when comes in the foreground start it , 
If I don't do anything in background code like remove the stop method , then it works in the foreground and as well in background.
Let me know if i am doing something wrong or if you can help me step by step
Thanks