Bill: Thanks a million for the wonderful explanation! Much appreciated.
Cheers! Reza. ----- Original Message ----- From: Bill Sandiford To: Reza - Asterisk Enthusiast ; TAUG Sent: Saturday, September 15, 2007 12:27 AM Subject: Re: [on-asterisk] CNAM - Caller ID Name > 1. Why dynamic CNAM issue is a big deal? >From a technical point of view it isn't usually a big deal at all. From a liability point of view it could be. Some larger carriers are worried about the implications if scam artists started setting their CNAM to things like "TORONTO POLICE" and started calling people fraudlently. My argument to the carriers has always been "Well you let us set the number and nothing is stopping the scam artists from setting the number to match the number of the police, so whats the big deal?" The usual answer I get is a confused look and a shrug of the shoulders. > 2. Why does the Name info have to be dug out each time from a shared > database (if its shared) based on the number (some carriers do this) by > the > carrier's lookup servers.... and then spit out to its subscribers? Well, in Canada it isn't done that way at all. The CNAM database method is how the CNAM info is looed up in the good old U S A. In the US carriers access a shard CNAM database and query the database for the CNAM for every call. In Canada we use a totally different method (described below) > 3. Why can't the NAME be sent with the NUMBER info from one carrier to > the > other? In Canada it is !!!! The CNAM in Canada is passed from carrier to carrier as part of the messaging that take place when a call is initiated. > 4. or .... Is transmitting NAME with the NUMBER simply a limitation on > the > switch the telcos carry? Most of the time if its not working its as a result of interoperability between varying switch types. If the trunks between carriers are SS7 then the CNAM will most certainly work properly. However must people using Asterisk don't have SS7, they have PRIs. The ISDN signalling between different switches expect CNAM to be passed in different ways. For example, a Nortel DMS (Bell Canada), expects the CNAM to be sent as part of the initial Q.931 call setup message. Lucent 5ESS switches (Telus, Rogers) expect it to be part of a subsequent progress message as a Facility IE. So, in order to get CNAM to work on your PRI, its important to know what method your carrier uses. I can tell you that Asterisk definately supports the Facility IE message because I was the one that initiated the feature request and did the testing for it back in April 2005. http://bugs.digium.com/view.php?id=4046 To enable CNAM by Facility IE set facilityenable=yes in zapata.conf. If you have SIP trunking, you are at the mercy of your carriers switch capabilites and their PSTN connectivity arrangments. Hope this helps clear things up for you !!! Regards, Bill Sandiford Telnet Communications 905-674-2000 x100 [EMAIL PROTECTED] IMPORTANT NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by email and delete the message. Thank you. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
