MWI activation in Polycom phone and Asterisk:

MWI activation in Polycom phone and Asterisk:

#vi /etc/asterisk/voicemail.conf
[default]
57644 => 1234,John Doe, John.Doe@xyz.com

#vi /etc/aterisk/sip.conf
[57644 ]
type=friend
host=dynamic
username=57644 
callerid="John Doe" <57644 >
secret=mypassword
mailbox=57644 

pbx CLI> sip show peer 57644
* Name : 57644
- - - -
- - - -
Mailbox : 57644
Call limit : 0
Max forwards : 0
Dynamic : Yes
Callerid : "John Doe" <57644>
MaxCallBR : 384 kbps
Expire : 205
- - - -
- - - -
Addr->IP : 192.168.2.10:5060
Defaddr->IP : (null)
Prim.Transp. : UDP
Allowed.Trsp : UDP
Reg. exten :
Def. Username: 57644
SIP Options : (none)
Codecs : 0x4 (ulaw)
Codec Order : (ulaw:20)
Auto-Framing : No
100 on REG : No
Status : Unmonitored
Useragent : PolycomSoundPointIP-SPIP_331-UA/3.3.2.0413
Reg. Contact : sip:57644@192.168.2.10


Asterisk automatically sends NOTIFY message to IP phone provided that the phone is registered correctly with Asterisk and Asterisk knows which voicemail box is associated with that extension. You can check that by issuing the asterisk CLI command #sip show peer
Reg. Contact : sip:57644@192.168.2.10 tells you that phone is successfully registered. 
Mailbox : 57644 tells you that Asterisk knows that voicemail box 57644 is associated with that phone. That association is defined in sip.conf.