Hi,
I copy here from the docs
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/9_1_1/ccmfeat/CUCM_BK_C3E0EFA0_00_cucm-features-services-guide-91_chapter_0110010.html#CUCM_TP_SFF7026D_00
Can you check it against your scenario?
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Presence Information
The presence status "on a call" is displayed for a user in the following situations:
- Outgoing Calls
- The user initiates a call from Cisco Jabber for Windows in Extend and Connect mode.
- The user initiates a call from a device that is configured as a remote destination which is routed using Unified CM or Unified CM with Unified CM SME.
- Incoming Calls
- The user answers a call on a device configured as a remote destination routed using Unified CM or Unified CM with Unified CM SME.
- The user answers a call routed to a device configured as a remote destination using Cisco Single Number Reach.
The presence status "on a call" is not displayed for a user in the following situations:
- When the user initiates a call from a device that is configured as a remote destination; the call is not routed using Unified CM or Unified CM with Unified CM SME.
- When the user answers a call on a device that is configured as a remote destination; the call is not routed using Unified CM or Unified CM with Unified CM SME.
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HTH,
Christos