Hi Erick,
the only carrier who knows the number is invalid is the LEC/CLEC
that owns the block. They probably will send back a 404 Not Found
or 604 in most cases. However unless you are directly connected
to them you may not get that response returned to
+1 on Glen's answer.
Intermediate carriers deal with enough FAS and other garbage that they
cannot trust every 404 or 604. We've determined that it's better to 503 a
possibly invalid number for the customer to later retry, than falsely 404 a
valid number and get complaints about how we trashed
ttp://www.linkedin.com/company/star-telecom-www.startelecom.ca-?trk=top_nav_home>
*From:* VoiceOps [mailto:voiceops-boun...@voiceops.org] *On Behalf Of *Calvin
Ellison
*Sent:* Monday, October 12, 2015 3:46 PM
*To:* Voiceops.org <voiceops@voiceops.org>
*Subject:* Re: [VoiceOps] SIP return message
