Question : 1-800 number 101

Hi,

1. How does one create 1-800 numbers? Do you buy a T1 line from telco and used that?

Thanks.

Answer : 1-800 number 101

1. The carrier is the phone company - aka telco.
2. 800 numbers are not defined by any protocol, they are simply forwarded to a RTN.

ISDN is a type of digital circuit, similar to a T1, if you had a ISDN/T1 you could have several DID's (Direct Inward Dial numbers). You could then attach 1 or more 800 numbers to each of these DID's by requesting this 800 number from your carrier. The best part about a ISDN/T1 circuit is that you can actually have more DID numbers than physical lines/channels, a single T1 can easily be bought with 200 DID numbers, it cost $20-30 for a block of 20-25 DID numbers.  The amount of calls you could receive would then only be restricted by the amount of channels you have turned on - typically 23 on ISDN and 24 on a T1, it does not matter that someone has already dialed a particular number, as long as another channel is available on the circuit.

If you had an analog system your 800 number would be limited by the amount of hunt lines you purchase with your main RTN.

SS7 - signaling system 7 is a complex multi-layered signaling protocol that is typically only used on the carrier side; since it uses its own network totally separate from the actual phone circuit you would most likely never see anything that has to do with SS7, unless you are setting up a carrier grade network for some sort of resellable phone service. This signaling system is the world wide standard for call setup, wireless service, 800/900 number routing.  SS7 defines how a 800 number travels across the carrier network to a particular RTN.

If you want to be truly overwhelmed in SS7 go here: http://www.pt.com/tutorials/ss7/tcap.html  - this discusses the particulars of 800 numbers and SS7.

Hope this isnt too much info.
Cheers!