Linksys Tribox SPA400 - Manual (Page 6)

Step 5 – Configure Trixbox Trunk.
Open your FreePBX interface:
http://trixbox.ip/admin/
Select Trunks -> Add SIP trunk
Complete the form with the details below:
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Outbound Caller ID: Blank
Never Override CallerID : Unticked
Maximum Channels: (the number of pstn lines plugged into the
SPA400)
Dial Rules: Leave Empty
Outbound Dial Prefix: Empty
Trunk Name: SPA400 (Can be anything you wish)
Peer Details:
allow=ulaw
canreinvite=no
context=from-trunk
dtmfmode=rfc2833
host=x.x.x.x
insecure=very
type=friend
user=SPA400
USER Context: Leave Blank
USER Details: Blank (Delete the default information)
Register String:
SPA400@x.x.x.x/SPA400
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Note : x.x.x.x should be where you enter the IP address of the
SPA400
Click Submit Changes.