asterisk users - Sep 2004 - My Cisco 7940 is not registering with Asterisk

I just got a Cisco 7940G phone running SIP firmware version POS3-06-1-00. I
unlocked the phone's config, and using the soft keys, I entered the SIP
Configuration menu and keyed in values for Name, Auth. Name, ProxyAddress
(where I gave my Asterisk server's IP address), etc.

The result is that I can make outgoing calls from this phone just fine
through my Asterisk server, but I cannot call the phone. With most SIP
phones, after you save the SIP settings, the phone registers with *, and you
see the registration message on the * console. But in my case, saving the
SIP settings had no effect, I saw no message that the phone registered.
Obviously, the phone can see the * server, because outgoing calls work.

Any ideas what I'm doing wrong? How do I force the 7940 to register? I have
other non-Cisco phones like Snom 200 that work just fine.

Here's my phone's SIP settings:

Line 1 Configuration
===================Name           201
Shortname      201
Authent. Name  201
Password       <none>
Display Name   201
Proxy Address  192.168.2.11 (the IP address of the Asterisk server)
Propxy Port    5060

And here's the relevant part of my sip.conf:

[general]
port = 5060
bindaddr = 0.0.0.0
disallow = all
allow = ulaw
allow = alaw

[201]
type=friend
username=201
secrethost=dynamic
context=dialout
callerid=201
dtmfmode=rfc2833
mailbox=201

Thanks in advance for any help.

Rana Dutt
Softel, Inc
Marlboro, NJ
(732) 810-6707 x200