Several people have asked questions about fone service, and I will attempt to explain, without being too wordy, (yeah, right!!) some basics.
Part 1- As for purely local fone svc, almost ALL end up getting to your home/business on copper pairs, otherwise known as just plain ol' wire.
I mentioned 'load coils', or loaded/unloaded pairs on another thread. Here's the deal: The fone co's consider a frequency bandwidth of 3000 Hertz to be as much as you need to talk, and, until recently, over which to send analog data.
In years past, almost ALL pairs were loaded, or had little donut-shaped inductance coils on them to make the 0-3000Hz bandwidth more 'talkable'.
Most analog modems will be equipped with enough 'error correction' to compensate for load coils, but, the downside is that your connect speed may vary from one time to the next.
We learned, years ago, that high-speed data, as low as 2.4Kbps for digital, high-speed analog (IE: 56Kbps), and anything up to and/or higher than T1 rate, 1.544 Mbps, only work reliably on unloaded pairs. T1 will ONLY work on unloaded pairs!
It's really easy for a phone man to use a test set to determine whether a pair is loaded or non-loaded. Trying to send data over loaded pairs is the leading cause of problems.
See: Load Coils and HERE
Another method, to save the number of copper pairs from the CO, (central office) is to use a Subscriber Line Carrier. Or SLC, which we call a 'slick'. SLC's can leave the CO on copper or fiber. It takes 2 copper pairs, one for transmit, and one for recieve, to get to the SLC cabinet in the field. From there, most SLS's will serve 96 customers.
You can see that instead of using 96 pairs for 96 customers, the fone co's can use only 2 pairs to serve the same 96 customers. If it's a copper SLC, you still get copper pairs to your home/business. If it's a fiber SLC, you MAY be able to get FITL, or Fiber In The Loop, as discussed in the other thread. But most of the time, you are still served by copper pairs.
Most SLC's, presuming 96 channels, operate at a T1 rate, or 1.544 Mbps, from the CO to the field unit, or SLC cabinet. Various types of modulating and de-modulating take place at the SLC cabinet and in the CO to enable 96 customers to be able to use dial-ups simultaneously.
If a fiber SLC AND FITL is available, you can get fiber all the way from the CO to your house, but it ain't cheap, and neither is the equipment to decode the fiber signal down to individual fone lines (talk) and data transmission lines.
[ 02-21-2003, 05:43 PM: Message edited by: CharlesLowry. ]
Part 1- As for purely local fone svc, almost ALL end up getting to your home/business on copper pairs, otherwise known as just plain ol' wire.
I mentioned 'load coils', or loaded/unloaded pairs on another thread. Here's the deal: The fone co's consider a frequency bandwidth of 3000 Hertz to be as much as you need to talk, and, until recently, over which to send analog data.
In years past, almost ALL pairs were loaded, or had little donut-shaped inductance coils on them to make the 0-3000Hz bandwidth more 'talkable'.
Most analog modems will be equipped with enough 'error correction' to compensate for load coils, but, the downside is that your connect speed may vary from one time to the next.
We learned, years ago, that high-speed data, as low as 2.4Kbps for digital, high-speed analog (IE: 56Kbps), and anything up to and/or higher than T1 rate, 1.544 Mbps, only work reliably on unloaded pairs. T1 will ONLY work on unloaded pairs!
It's really easy for a phone man to use a test set to determine whether a pair is loaded or non-loaded. Trying to send data over loaded pairs is the leading cause of problems.
See: Load Coils and HERE
Another method, to save the number of copper pairs from the CO, (central office) is to use a Subscriber Line Carrier. Or SLC, which we call a 'slick'. SLC's can leave the CO on copper or fiber. It takes 2 copper pairs, one for transmit, and one for recieve, to get to the SLC cabinet in the field. From there, most SLS's will serve 96 customers.
You can see that instead of using 96 pairs for 96 customers, the fone co's can use only 2 pairs to serve the same 96 customers. If it's a copper SLC, you still get copper pairs to your home/business. If it's a fiber SLC, you MAY be able to get FITL, or Fiber In The Loop, as discussed in the other thread. But most of the time, you are still served by copper pairs.
Most SLC's, presuming 96 channels, operate at a T1 rate, or 1.544 Mbps, from the CO to the field unit, or SLC cabinet. Various types of modulating and de-modulating take place at the SLC cabinet and in the CO to enable 96 customers to be able to use dial-ups simultaneously.
If a fiber SLC AND FITL is available, you can get fiber all the way from the CO to your house, but it ain't cheap, and neither is the equipment to decode the fiber signal down to individual fone lines (talk) and data transmission lines.
[ 02-21-2003, 05:43 PM: Message edited by: CharlesLowry. ]