[SIPForum-discussion] FW: CLI Validation

[Chris Nicholson]

Hi Wissam,

Unfortunately, with international calling, sometimes you simply can not tell for sure.  Sometimes, you will receive something like <sip:0 at gateway:5060> or  a string of 0's or a string of 1's.  In these cases you can tell call-id is not valid, because it does not resemble a number.  Other times, you may receive a wrong call-id that looks like a valid number, so you have no choice but to pass it on as is. (I believe it may be a trunk number.)

A second issue you want to be aware of is privacy...  Sometimes you will receive "anonymous" <sip:0 at gateway:5060>  or <sip:anon at gateway>, or "anonymous" <sip:anonymous at gateway:5060>.  The last case is valid if the privacy indicator header is present.  This means, the caller has requested privacy and a privacy indicator was set in the ISUP and the VOIP gateway has carried that information forward.  Some gateways don't include the Privacy indicator, but do set the call-id anonymous.  This isn't very good behavior, but I have seen it.  See RFC 3323 for privacy and RFC 3325 for P-Asserted-Identity header, which your VOIP gateway may support if they receive a call-id along with a privacy indicator.

Hope that helps,
-Chris


From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Wissam Ismail
Sent: Monday, May 23, 2011 4:43 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] FW: CLI Validation

Hello All,

we buy a white route to a destination from our suppliers and must support CLI,  Sometimes we are facing mixing route with bad quality and without CLI,
my question is how to detect from SIP call that the caller number appear on the endures phones?


Regards,
.............................................
Wissam Ismail

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