You need to enable APNS (Apple push notification) for this. There is a setting on the CUCM to enable this and also enable OAuth Refresh login settings on Expressway for faster Jabber login.
Refer to this document on how to do this and minimum required versions:
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/push_notifications/cucm_b_push-notifications-deployment-guide/cucm_b_push-notifications-deployment-guide_chapter_01.html
Table 2. Minimum Release Requirements for Push Notifications Solution Minimum Releases
Calling with IM and Presence | Cisco Unified Communications Manager 11.5(1)SU3 Note | For HTTPS Proxy support, the minimum release is 11.5(1)SU4 for 11.x releases, and 12.0(1)SU2 for 12.x releases. |
IM and Presence Service 11.5(1)SU3 Cisco Jabber 11.9 Cisco Expressway X8.10.1 ( if MRA is deployed)
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-Terry