asterisk users - Dec 2005 - Problem with Xlite free phone(Xten)

Looking for a low-cost but good quality (i.e. value) service provider 
for US to Japan calls.  Either a low monthly unlimited rate under $30 or 
very low per minute rates.  I'm using SIP and analog phones w/Asterisk.  
The called party in Japan probably has PSTN phones with few exceptions.

Hi,
  got this when dial to Xlite User agent registered as 1234. BUt it can dial
out.

-- Executing Dial("SIP/1235-e9b6", "SIP/1234") in new stack
    -- Called 1234
    -- Got SIP response 486 "Busy" back from 202.54.195.89
    -- SIP/1234-7c6b is busy
  == Everyone is busy/congested at this time (1:1/0/0)
  == Auto fallthrough, channel 'SIP/1235-e9b6' status is 'BUSY'

Configuration in sip.conf for 1234 is as

[1234]
type=friend
host=dynamic
context=default
username=1234
secret=1234
;regexten=1234






Abhishek