Here's what I have

For Outgoing:

Code:
disallow=all
username=myDIDNumber
type=peer
secret=mypassword
qualify=yes
nat=yes
insecure=port,invite
host=central01.voipwelcome.com
fromuser=myDIDnumber
fromdomain=codeblue.voipo.com
context=from-sip
allow=ulaw
For incoming:
Code:
disallow=all
type=peer
secret=mySIPpassword
qualify=yes
nat=yes
insecure=port,invite
host=central01.voipwelcome.com
context=from-sip (this will be different possibly)
allow=ulaw
My register string is like yours, but with the / and DID after it.