Subject: [sipcore] callinfo-spam: review of sip.call-info.spam feature capability indicator

From: Christer Holmberg <[email-masked]>
Date: Thu, 6 Apr 2017 08:17:53 +0000

Hi,

In Chicago, I was asked to take a look at the sip.call-info.spam feature
capability indicator (fci), defined and used in
draft-ietf-sipcore-callinfo-spam-00.

General:

Q1:     I think there should be some more information on how the fci is
used. For example, including a REGISTER response which contains the fci.

Q2:     Related to Q1, there is no text regarding the procedures of the
receiver (i.e., the called party) of the fci.

Section 3:

Q3:    s/a new feature tag/a new feature capability indicator

Q4:    The text says:

"indicates whether the terminating carrier will remove untrusted
information."

The text should also include the name of the feature that the terminating
carrier supports. It would also be good to mention how/when the support is
indicated in the section.

Something like:

³that the terminating carrier can use in a REGISTER response in order to
indicate support of XXX, and that it will remove untrusted information.²

Q5:    The text says:

"SIP entities MUST add a new Call-Info "info" header field instance,
rather than add parameters to an existing one.²

What SIP entities?

Q6:    I think the sentence above should also indicate from where
untrusted information will be removed. I assume it is from the Call-Info
header field.

Q7:    The text above talks about removing information, which the
description in section 8.2 also talks about adding and altering
information. I think the text in sections 3 and 8.2 need to be aligned.

Section 8.2:

Q8:    In general, the registration of the fci looks ok. See Q7.

Section 9:

Q9:    The text says:

"SIP entities MUST remove any parameters defined here that were provided
by untrusted third parties.²

What SIP entities?

Regards,

Christer