Your interface with the smart jack is an RJ-48C connector, which is basically an RJ-45. When wiring the RJ-45 use the wiring spec of the TIA/EIA 568B color code. This color code is as follows…

However only Pin 1, Pin2, Pin 4 and Pin 5 are used… You only need to wire the 4 pins crimped to the RJ-45 connector. In the end the White/Blue and Blue pair of wires is your Transmit Ring and Tip and the White/Orange and Orange pair of wires is your Receive Ring and Tip. This basic wiring is what comprises a 4-wire T1 circuit with current Telco service today.

If you wanted to create a simple hardware loopback; you could simply connect Pin 1 to Pin 4 and connect Pin 2 to Pin 5. This would connect the Receive Ring with the Transmit Ring and connect the Receive Tip with the Transmit Tip. A connection like this would loop all data back to the Telco. You can fabricate a device like this with an RJ-45 connector and two wires. When you want to check your wiring you can; look at the smart jack (if you have access to it) and watch the ‘Alarm’ go off when you connect the loopback or call the Telco and have them verify the alarm is off. This is a simple way to check your T1 circuit all the way to your device.

The NANP defined how areas would be numbered as well, areas being large area or Local Area Transport Areas (LATA). All calls in the area where charged at a predefined rate and in the 80′s that changed and where split into smaller area. However the Area Code or Numbering Plan Area are the same. So the Area Code / NPA for Pittsburgh is 412 this defines the Numbering Plan Area. Inside of the NPA there are several Exchanges or Numbering Plan Exchanges these are defined as NXX. This is the BAY/229 in Bayside. The last 4 digits of a phone number are the subscriber line and again that is private data.

So looking at a number like 412-229-0123 you can tell that it is in 412 or Pittsburgh. Inside of Pittsburgh the Exchange area or NXX is 229 or Bayside and the Subscriber is 0123. Well wouldn’t it be perfect if all exchanges matched like 229 is Bayside? Well 224 is also Bayside and that doesn’t work on a phone with the number encoding. Remember the NANP was introduced in 1947 and everyone owns a phone, so area were numbered outside of the first three letters encoded to the digits on a phone. You don’t call ‘Mabel’ anymore. There is a database published that Long Distance providers subscribe to for call routing. You can find pretty up to date version that are freely searchable on the Internet, just Google ‘npa nxx’ and you will find one. You can then locate a person down to the city they live in.