[asterisk-users] G729 Confusion

[Matt]

I've purchsed 5 g729 licenses from digium, but am a little confused
about why things are acting the way they are.

When I do show g729 I see:
0/0 encoders/decoders of 5 licensed channels are currently in use

My sip.conf starts out:
[general]
disallow=all
allow=ulaw
allow=g726

then my hosts look like this:

[6016716]
username=6016716
accountcode=75415
type=friend
secret=obsurified
qualify=yes
port=5060
nat=yes
mailbox=6016716 at default
host=dynamic
dtmfmode=rfc2833
context=from-internal
canreinvite=no
callerid="Test VoIP Accounts" <6016716>

All works fine, however if I make a change so it reads:
[6016716]
disallow=all
allow=g729
username=6016716
accountcode=75415
type=friend
secret=obsurified
qualify=yes
port=5060
nat=yes
mailbox=6016716 at default
host=dynamic
dtmfmode=rfc2833
context=from-internal
canreinvite=no
callerid="Test VoIP Accounts" <6016716>

and reload, strange things begin to happen.  A show g729 shows this:
5/0 encoders/decoders of 5 licensed channels are currently in use
and suddenly I can not hear anything if I try to make a call.    From
observation, it almost seems like other units on the network are using
the g729 codecs, but doesn't my sip.conf prohibit g729 unless
expressly allowed?!  Why would allowing g729 under one extension allow
everyone else to suddenly start using g729?