[Asterisk-Users] Message waiting indicator

[Rich Adamson]

> What is required to get the mwi to work?  Is it more of a phone subject
> or *?  I have the mailbox= line in sip.conf, but only one extension is
> named, and in some of the examples, I have seen that there are two...
> What is that all about and how does it affect the extensions.conf and
> voicemail.conf?

I think the examples that you might have looked are suggesting
that when a voicemail is left for a single extension, you "can" place
definitions in your sip.conf file that turn on the MWI (message
waiting indicator) LED on more then one phone. (I'll leave that up to 
you to figure out whether that is a feature of use to you.)

Asterisk will occasionally look in the
 /var/spool/asterisk/voicemail/default/3008/INBOX
directory (where 3008 represents the extension number), and if a certain
file exists, send a sip message to the extn(s) that you defined
in sip.conf as "mailbox=3008".

The sip message sent to the phone (in hex using a packet sniffer) 
looks like:

0020: c1 5b 13 c4 13 c4 01 e2 58 97 4e 4f 54 49 46 59 | Á[.Ä.Ä.âX—NOTIFY
0030: 20 73 69 70 3a 33 30 30 38 40 32 30 35 2e 32 31 |  sip:3008 at 205.21
0040: 32 2e 31 39 33 2e 37 31 20 53 49 50 2f 32 2e 30 | 2.173.91 SIP/2.0
0050: 0d 0a 56 69 61 3a 20 53 49 50 2f 32 2e 30 2f 55 | ..Via: SIP/2.0/U
0060: 44 50 20 32 30 35 2e 32 31 32 2e 31 39 33 2e 31 | DP 205.212.193.1
0070: 30 31 3a 35 30 36 30 3b 62 72 61 6e 63 68 3d 7a | 01:5060;branch=z
0080: 39 68 47 34 62 4b 33 63 31 63 61 35 65 31 0d 0a | 9hG4bK3c1ca5e1..
0090: 46 72 6f 6d 3a 20 22 61 73 74 65 72 69 73 6b 22 | From: "asterisk"
00a0: 20 3c 73 69 70 3a 61 73 74 65 72 69 73 6b 40 32 |  <sip:asterisk at 2
00b0: 30 35 2e 32 31 32 2e 31 39 33 2e 31 30 31 3e 3b | 05.212.193.101>;
00c0: 74 61 67 3d 61 73 35 37 63 63 64 33 32 65 0d 0a | tag=as57ccd32e..
00d0: 54 6f 3a 20 3c 73 69 70 3a 33 30 30 38 40 32 30 | To: <sip:3008 at 20
00e0: 35 2e 32 31 32 2e 31 39 33 2e 39 31 3e 0d 0a 43 | 5.212.193.91>..C
00f0: 6f 6e 74 61 63 74 3a 20 3c 73 69 70 3a 61 73 74 | ontact: <sip:ast
0100: 65 72 69 73 6b 40 32 30 35 2e 32 31 32 2e 31 39 | erisk at 205.212.19
0110: 33 2e 31 30 31 3e 0d 0a 43 61 6c 6c 2d 49 44 3a | 3.101>..Call-ID:
0120: 20 34 34 66 39 31 38 36 64 34 30 62 30 31 35 33 |  44f9186d40b0153
0130: 30 36 37 39 32 30 31 39 64 33 36 39 35 66 36 31 | 06792019d3695f61
0140: 36 40 32 30 35 2e 32 31 32 2e 31 39 33 2e 31 30 | 6 at 205.212.193.10
0150: 31 0d 0a 43 53 65 71 3a 20 31 30 32 20 4e 4f 54 | 1..CSeq: 102 NOT
0160: 49 46 59 0d 0a 55 73 65 72 2d 41 67 65 6e 74 3a | IFY..User-Agent:
0170: 20 41 73 74 65 72 69 73 6b 20 50 42 58 0d 0a 45 |  Asterisk PBX..E
0180: 76 65 6e 74 3a 20 6d 65 73 73 61 67 65 2d 73 75 | vent: message-su
0190: 6d 6d 61 72 79 0d 0a 43 6f 6e 74 65 6e 74 2d 54 | mmary..Content-T
01a0: 79 70 65 3a 20 61 70 70 6c 69 63 61 74 69 6f 6e | ype: application
01b0: 2f 73 69 6d 70 6c 65 2d 6d 65 73 73 61 67 65 2d | /simple-message-
01c0: 73 75 6d 6d 61 72 79 0d 0a 43 6f 6e 74 65 6e 74 | summary..Content
01d0: 2d 4c 65 6e 67 74 68 3a 20 33 37 0d 0a 0d 0a 4d | -Length: 37....M
01e0: 65 73 73 61 67 65 73 2d 57 61 69 74 69 6e 67 3a | essages-Waiting:
01f0: 20 79 65 73 0a 56 6f 69 63 65 6d 61 69 6c 3a 20 |  yes.Voicemail: 
0200: 31 2f 30 0a                                     | 1/0.

where if you look closely at the text on the right side, you can see
data like "Missages-Waiting: yes" in the packet. (You might want to read
the RFC that defines what the sip protocol is all about, it will help
you understand.)

The hardware/software sip phone is supposed to translate that sip msg
and turn on the LED on the phone's panel. Exactly how "each" phone
implements that function is up to the phone manufacturer, and like 
many things in the voip space, some get right while others seem to
struggle with the simple things in life.

If you don't have a packet sniffer, then from the asterisk command
line, enter "sip debug" and dig through the display for the equivalent
message. The interesting piece will look something like:

To: <sip:3008 at 205.212.193.91>
Contact: <sip:asterisk at 205.212.193.101>
Call-ID: 73fecd1b0818b5a104f19b7270c06475 at 205.212.193.101
CSeq: 102 NOTIFY
User-Agent: Asterisk PBX
Event: message-summary
Content-Type: application/simple-message-summary
Content-Length: 37
Messages-Waiting: yes     <<============
Voicemail: 1/0
 (no NAT) to 205.212.193.91:5060

Sip read: I>
SIP/2.0 200 Ok         <<=============

If your phone's display or MWI LED doesn't function, then use the above
to diagnose which component is not working right.

The SIP RFC and "sip debug" command are your friends; get to know them.

Rich