[Asterisk]Configuration

path: /etc/asterisk/

sip.conf

[111]
type=friend
secret=111
qualify=yes
nat=no
host=dynamic
canreinvite=no
mailbox=111
context=sip on-net

[222]
type=friend
secret=222
qualify=yes
nat=no
host=dynamic
canreinvite=no
mailbox=222
context=sip on-net

extensions.conf
[sip on-net]
exten => 111,1,dial(sip/111,10,r)
exten => 111,2,voicemail(u111@default)
exten => 111,222,voicemail(b111@default)
exten => 222,1,dial(sip/222,10,r)
exten => 222,2,voicemail(u222@default)
exten => 222,111,voicemail(b222@default)
exten => 500,1,voicemailmain()
exten => _XXX,1,dial(sip/${EXTEN},,r)
exten => _XXXXX,1,dial(sip/$EXTDN},,r}

voicemail.conf

[default]
111 => 111,111,111@asterisk.com,111@phone.com
222 => 222,222,222@asterisk.com,222@phone.com