SIP:Alert-Info header

Inbound Calls

Alert-Info is handled when received in INVITE

It's for endpoints connected to a non-innovaphone PBX that sends Alert-Info in INVITE.
The heuristic method or processing Alert-Info is as follows:

An incoming call is tagged as "internal" if either:

• parameter "call-type" is "internal"
• parameter "info" is "alert-internal"
• uri contains "Bellcore-dr1"
• uri contains "internal" (e.g. urn:alert:source:internal (RFC 7462))

An incoming call is tagged as "re-call" (return from failed blind transfer) if either:

• parameter "call-type" is "callback"
• parameter "info" is "alert-recall" or "alert-community1"
• uri contains "Bellcore-dr3/"
• uri contains "service:recall" (e.g. urn:alert:service:recall:transfer (RFC 7462))

An incoming call is tagged as "emergency" if either:

• parameter "info" is "alert-emergency"

Otherwise an incoming call is tagged as "external".

Outbound Calls

Alert-Info when sending INVITE

Alert-Info header is sent in INVITE and the header content is selected according to RFC 7462:

• <urn:alert:source:internal> if this call is tagged as "Internal"
• <urn:alert:source:external> if this call is tagged as "Normal"
• <urn:alert:service:recall:transfer> if this call is tagged as "Recall" (failed blind transfer)

Alert-Info is handled when received in provisional response

An outgoing call is tagged as "queued" (call-waiting) if "urn:alert:service:call-waiting" is present in Alert-Info header.