Registering a SIP phone from the Public

I need to register a sip phone (polycomy ip 550) from the public cloud to my Asterisk 1.4 Srv.

However, when I do a sip show peers the peer in question comes up unreachable.

this is my sip.conf entry. What am i doing wrong?

[1024]
type=friend
secret=1024
username=1024
host=24.46.166.98
dtmfmode=rfc2833
context=users
canreinvite=no
allow=ulaw
nat=yes
dtmfmode=rfc2833
qualify=yes
mailbox=1024@default

try setting the port

is your firewall on 24.46.166.98 open for 5060 ?