Three ways a call can enter
Choose the path
Ask
Who provides the trunk?
Buyer
Five9
Five9 ITSP is the first
story.
Carrier
Yours
Your ITSP to Five9 SBCs
is the second.
Carrier
Owned
Avaya, Cisco, or
Asterisk is the third.
Gateway
Link
Internet, VPN, or Direct
Connect is the
Gateway
Write
The design names one
story.
Admin
Name one before you open a firewall ticket.
Sources and go deeper
Technical requirements PDF
.
vendor
. last checked 2026-10. Fetched for this lab in October 2026. Re-read before you buy hardware or open a firewall.
SIP trunk options chapter
.
vendor
. last checked 2026-10.
RFC 3261
.
rfc
. last checked 2026-10.
RFC 3550, RTP
.
rfc
. last checked 2026-10.
RFC 3551, RTP profile for audio and video
.
rfc
. last checked 2026-10.
ITU-T G.711
.
standard
. last checked 2026-10.
ITU-T E.164, international public telecommunication numbering
.
standard
. last checked 2026-10.