Aastra 53i Release Note page 103

Aastra Web UI
Per-Line Configuration
1 Click on Advanced Settings->Line <N>->Advanced SIP Settings.
2 The "Missed Call Summary Subscription" field is disabled by default. To enable this field, check
the box. This feature allows missed calls that have been redirected by the server, to be incremented
in the missed calls indicator on the phone it was initially directed to.
3 Click
RN-001029-00, Rev 03, Release 2.1
to save your changes.
5i Series IP Phone Release Notes
Sylantro Interoperability Features
97