Features/Extension Monitoring/Connected

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Individual Subscriptions (RFC 4235) Event List Subscriptions (RFC 4662)


  1. Ext 1 monitors Ext 2
  2. Ext C calls monitored Ext 2
  3. Ext 2 accepts the incoming call from Ext C


Example#1 SIP Message Flow with PBXnSIP PBX
  1. Ext 2 sends NOTIFY to monitoring Ext 1
    • the subscription event is dialog
    • the subscription is active (not expired).
    • the dialog state has been changed on the recipient side (Ext 2)
    • the dialog state is confirmed
    • the call-id the dialog state change refers to
    • the <remote> element containing the identity / target uri of Ext C
    • the <local> element containing the identity / target uri of Ext 2
  2. The NOTIFY is accknowledged by Ext 1
Individual Subscriptions (RFC 4235) Event List Subscriptions (RFC 4662)
Received from ...

NOTIFY sip:Ext 1
Via: ...
From: <sip:Ext 2;user=phone>;tag=be02f228a5
To: <sip:Ext 1>;tag=ooksd25zj3
Call-ID: 3c26702ca6e8-iqdrmmqfu7ph
CSeq: 10010 NOTIFY
Max-Forwards: 70
Contact: ...
Event: dialog
Subscription-State: active;expires=190
Content-Type: application/dialog-info+xml
Content-Length: 447

<?xml version="1.0"?>
 <dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info"
  version="3"
  state="full"
  entity="sip:Ext 2">
  <dialog
   id="dummy"
   call-id="3c2e4a6f09c4-f4s1udjura9v@snom360-000413230D7D"
   direction="recipient">
   <state>confirmed</state>
   <remote>
    <identity>sip:Ext C</identity>
    <target uri="sip:Ext C"/>
   </remote>
   <local>
    <identity>sip:Ext 2</identity>
    <target uri="sip:Ext 2"/>
   </local>
  </dialog>
 </dialog-info>

------------------------------------------------------------------

Sent to ...

SIP/2.0 200 Ok
Via: ...
From: <sip:Ext 2...
To: <sip:Ext 1>...
Call-ID: ...
CSeq: 10010 NOTIFY
Content-Length: 0
Received from ...:

NOTIFY sip:Ext 1...
Via: ...
From: <sip:Ext 1...
To: <sip:Ext 1...
Call-ID: ...
CSeq: 20171 NOTIFY
Max-Forwards: 70
Contact: ...
Event: dialog
Subscription-State: active;expires=116
Content-Type: application/dialog-info+xml
Content-Length: 448

<?xml version="1.0"?>
 <dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info"
  version="68"
  state="full"
  entity="sip:Ext 2">
  <dialog
   id="dummy"
   call-id="3c3e0a2e4baf-v4to21vv68q5@snom360-000413230D7D"
   direction="recipient"
  <state>confirmed</state>
  <remote>
   <identity>sip:Ext C</identity>
   <target uri="sip:Ext C"/>
  </remote>
  <local>
   <identity>sip:Ext 2</identity>
   <target uri="sip:Ext 2"/>
  </local>
  </dialog>
 </dialog-info>

------------------------------------------------------------------

Sent to ...:

SIP/2.0 200 Ok
Via: ...
From: <sip:Ext 1...
To: <sip:Ext 1...
Call-ID: ...
CSeq: 20171 NOTIFY
Content-Length: 0
Result#1: Busy Lamp Field (BLF)
The LEDs of the function keys configured as "Extension" / "BLF" (from 7.1.33) stay lit. The BLF feature is NOT AVAILABLE when using event list subscription.
Result#2: "Calls" screen

The "Calls" screen on snom360/370 displays is updated, e.g. Ext C = 535 and Ext 2 = 484 are connected:



Example#2 Asterisk (1.4.X unpatched):
  1. Ext 2 sends NOTIFY to monitoring Ext 1
    • the subscription event is dialog
    • the subscription is active (not expired).
    • the dialog state has been changed on the recipient side (Ext 2)
    • the dialog state is confirmed
  2. The NOTIFY is accknowledged by Ext 1
Asterisk does NOT support this feature (1.2 / 1.4).
Individual Subscriptions (RFC 4235) Event List Subscriptions (RFC 4662)
NOTIFY sip:Ext 1...
Via: ...
From: <sip:Ext 2>...
To: <sip:Ext 1>...
Contact: <sip:Ext 2>
Call-ID: ...
CSeq: 111 NOTIFY
User-Agent: Asterisk PBX
Max-Forwards: 70
Event: dialog
Content-Type: application/dialog-info+xml
Subscription-State: active
Content-Length: 205

<?xml version="1.0"?>
 <dialog-info xmlns="urn:ietf:params:xml:ns:dialog-info"
  version="9"
  state="full"
  entity="sip:Ext 2">
  <dialog id="2015">
   <state>confirmed</state>
  </dialog>
 </dialog-info>

----------------------------------------------------------------------

Sent to ...:

SIP/2.0 200 Ok
Via: ...
From: <sip:Ext 2>...
To: <sip:Ext 1>...
Call-ID: ...
CSeq: 111 NOTIFY
Content-Length: 0
Asterisk does NOT support this feature (1.2 / 1.4).
Result#1: Busy Lamp Field (BLF)
The LEDs of the function keys configured as "Extension" / "BLF" (from 7.1.33) stay lit. Asterisk does NOT support this feature (1.2 / 1.4).
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