asterisk users - Apr 2005 - Cant respond to prompts from SPA1001

Hello,

I have a Sipura SPA1001 which for some reason cannot respond to 
Asterisk's prompts, for example the voicemail password or "Enter an 
Extension".  Asterisk seems to not recieve the tones.  I can dial my 
office PBX and answer prompts through the SPA1001, and Asterisk responds 
when I use my SPA2001.

Any suggestions?  Thanks in advance.

Ted