[Help]: Stuttered Dial tone with aastra phones

I have a network of 10 aastra 9112i’s run off of an Asterisk server. Everything works great except for the mwi/stuttered dial tone has never worked. I have contacted Aastra tech support, but they assure me that it’s a problem with the server.

Here’s my voicemail.conf

[general]

[office]
808 => ???
807 => ???,user
806 => ???,user
802 => ???,user
800 => ???,user
888 => ???,user
auto => ???,Automatic Answer

=========================
and my sip.conf

[100]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=100@office
host=192.168.1.119
dtmfmode=rfc2833
dial=SIP/100
context=from-internal
canreinvite=no
callgroup=
callerid=Entrance <100>
call-limit=4
accountcode=
call-limit=50

[800]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=800@office
host=192.168.1.118
dtmfmode=rfc2833
dial=SIP/800
context=from-internal
canreinvite=no
callgroup=
callerid=Roger <800>
call-limit=4
accountcode=
call-limit=50

[802]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=802@office
host=192.168.1.105
dtmfmode=rfc2833
dial=SIP/802
context=from-internal
canreinvite=no
callgroup=
callerid=Tim <802>
call-limit=4
accountcode=
call-limit=50

[803]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=803@office
host=192.168.1.115
dtmfmode=rfc2833
dial=SIP/803
context=from-internal
canreinvite=no
callgroup=
callerid=Reception <803>
call-limit=4
accountcode=
call-limit=50

[805]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=805@office
host=192.168.1.113
dtmfmode=rfc2833
dial=SIP/805
context=from-internal
canreinvite=no
callgroup=
callerid=Office <805>
call-limit=4
accountcode=
call-limit=50

[806]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=806@office
host=192.168.1.107
dtmfmode=rfc2833
dial=SIP/806
context=from-internal
canreinvite=no
callgroup=
callerid=Mary <806>
call-limit=4
accountcode=
call-limit=50

[807]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=807@office
host=192.168.1.100
dtmfmode=rfc2833
dial=SIP/807
context=from-internal
canreinvite=no
callgroup=
callerid=Sue <807>
call-limit=4
accountcode=
call-limit=50

[808]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=808@office
host=192.168.1.103
dtmfmode=rfc2833
dial=SIP/808
context=from-internal
canreinvite=no
callgroup=
callerid=Tyler <808>
call-limit=4
accountcode=
call-limit=50

[809]
type=friend
secret=???
record_out=Adhoc
record_in=Adhoc
qualify=yes
port=5060
pickupgroup=
nat=yes
mailbox=809@office
host=192.168.1.102
dtmfmode=rfc2833
dial=SIP/809
context=from-internal
canreinvite=no
callgroup=
callerid=Old Office <809>
call-limit=4
accountcode=
call-limit=50

Thanks in advance!