> 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 


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 !!!


Bill Sandiford
Telnet Communications
905-674-2000 x100

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