When calling from the Patton M-ATA device, to any number (internal extension or outside number) and capturing the call using Wireshark, I get the error. No problems calling to the Patton device.
So the 404 error is not fired by your device but by the SIP peer, isn't it ?
Then you need to analyze configuration/logs of other side. Your call is rejected for a reason known to the peer administrator only.
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