asterisk users - May 2005 - wip 5000 and using write msg on the phone - anyone?

I have a couple WIP 5000 phones, They are working great.
I can use sendtext() and send message to the phone.

However, when I select Messages menu on the phone, then
write message, I enter a phone extension, some short message
and click send. I get "FAILED" on the screen.

I dont see anything on the asterisk console that the phone even
tried to "connect" and send a message or anything.

Has anyone tried to use the write msg feature of the phone.

I was hoping there would at least have been some error message
on the asterisk console but there was not.

Thanks for any suggestions.

Jerry