Canadian TV, Computing and Home Theatre Forums banner
61 - 65 of 65 Posts

·
Registered
Joined
·
2 Posts
An in depth account on why toll free calling is tricky

You raise some interesting points where things get messy.

In the PSTN world, the caller's ANI and the charge ANI are virtually always the same for single-line business and home phone services. The telco makes sure of this as it's how they keep track of billing.

ANI and Caller ID are two separate things. ANI is supposed to always be set (or at least filtered) by the telco. Caller ID can be whatever you want. ANI is an integral part of the PSTN, whereas Caller ID is a value-added service added after the fact so the telcos could charge you more money.

If your telco allows it, you can spoof your Caller ID to whatever you want, but the ANI should always be set to a number the telco has provided to you.

Here is where the mess starts: ITSPs (Internet Telephony Service Providers, or commonly referred to as VoIP providers) are treated more like customers rather than actual facilities-based telcos. Today, they sit somewhere in the middle; not quite a telco but also more abilities than a typical customer.

ITSPs often use multiple carriers (actual facilities-based telcos) to provide better service availability, better rates, and redundancy.

Say your ITSP buys your phone number from Carrier A, but routes all of your outbound calls with Carrier B.

Carrier A should only allow the Charge ANI to be set to numbers they issue the ITSP. Same with Carrier B.

When you place an outbound call, the Charge ANI determines who will pay for the call. With systems today, the Charge ANI isn't that important because billing can be done based on SIP CDRs or other means. When it's set to a number you don't know about, you don't care because your call still goes through.

When you call a toll free number, it's a different ballgame. When a business has a toll free number, they agree to pay for all calls delivered to their toll free number. This means *YOUR* phone number expects to get paid by the business, rather than you, for the long distance charges. The business you call (or more likely, their phone company) knows who to compensate based on the Charge ANI.

So we come back to your phone number being provided by Carrier A, but your ITSP routes your calls out through Carrier B. Carrier B doesn't want to carry the call for free; they want their compensation! Thus, Carrier B will not allow the Charge ANI to be a number that belongs to their competitor, Carrier A, because then the wrong carrier receives compensation.

The solution here is to make sure all toll free calls are terminated by Carrier A. This way your phone number is used as the Charge ANI and then you are able to call all numbers that are willing to pay for calls from your area.

The Charge ANI is also used for routing decisions. If you call a national company with call several centres, they may rely on your Charge ANI to connect you to the call centre that serves your area.

Also, this doesn't go only by province. Routing can be done based on rate centre as well. Perhaps a company has a Victoria local number and a toll free. This company only wants to serve customers from BC and Alberta. Their toll free service will be set up to only accept calls from BC & AB. Furthermore, they may play a message to callers from Victoria asking them to hang up and call the local number instead.

If you are in Vancouver but a Victoria ANI is used, you will not be able to get through on the toll free number.

Coming back to the problem ITSPs have: sometimes they are treated as a customer and not a telco. In this case, they may have *their own* BTN used as the Charge ANI rather than their customer's BTN. In this case, calls end up being restricted to the ITSP's local calling area rather than the customer. It seems like this is the problem the original poster experienced.
 

·
Registered
Joined
·
13 Posts
Thanks for the great explanation. Worth adding to an FAQ.

For the benefit of the acronym-impaired, such as myself:
  • ANI = Automatic Number Identification (service which passes caller's number to callee)
  • BTN = Billing Telephone Number
 

·
Registered
Joined
·
33 Posts
seem to fixed for me now also

calling 800-437-7950 reads the same ANI for both calling and charge

(before, charge ANI was 519..)
 
61 - 65 of 65 Posts
Top