All circuits are busy with VOipbuster

Hi!
I am using VOipbuster on my trixbox as the main trunk.

I put this

[code]
allow=ulaw&alaw
canreinvite=yes
context=from-pstn
disallow=all
dtmfmode=inband
fromdomain=sip.voipbuster.com
host=sip.voipbuster.com
insecure=very
nat=yes
qualify=yes
secret=MYPASSWORD
srvlookup=yes
type=peer
username=MYUSERID
authuser=MYUSERID
fromuser=MYUSERID
sendrpid=yes
[code]

and in
Register String
sip.voipbuster.com

I did not set anything else (except the trunk name) in this EDIT SIP TRUNK page...

Concerning the ADD ROUTE page, i am using the default one with the 9|.
i put the trunk sequence as VOIPBUSTER
I did not change change anything else in this page....

I am using the eyebeam software as a SIP phone.
When i call from my SIPphone i do 9 00 44 ...... for the UK, 9 00 1 for the USA...
but i have the trixbox saying all circuits are busy.

What am i doing wrong?
thanks for your help

Nic