"Contrary to popular belief, each channel of a T1 has room for the CID. Remember, it's only presented between the 1st and 2nd ring (and again between 2 other rings 7 & 8?). It requires no overhead data space, it's sent as a modem signal @ 1200 (?) baud. You can hear it with a buttset in monitor mode.
Well, yes and no. Yes, each 64K channel of a T1 circuit is designed for 56K of bandwidth for voice communications and 8K for signalling. What happens in the 8K is up to the service provider and the terminal equipment's ability to work with it.
No, you can't monitor an individual T1 channel by connecting to the circuilt with a butt set to monitor for caller ID, or FSK data. If the T1 circuit lands on a channel bank or an IAD that converts the T1 into POTS circuits, and those channels (DS0s) are provisioned for such, then yes, a butt set will work on an individual FXS channel during the initial ring cycle through the monitored burst of data being sent.
One thing that is important here: Most true T1 circuits are meant for long-distance calling only. These circuits originate in toll offices, not end offices. Toll offices are at a layer above the end offices (end offices provide all of the end-user demands), while toll offices just boot high-volume traffic up a level to reduce bottlenecks.
For example (Cities are for figurative purposes only): A customer in Hackensack, NJ mass-calls numbers in Waukeegan, IL for a mass marketing campaign. Using a PRI or POTS services, these calls will originate in the Hackensack end office, bump up to the Newark, NJ toll office, then to the long distance service provider's office, across the LD network that hops through Dallas and Denver, then back down to the local toll office in Chicago that drops it down to the end office in Waukeegan.
A T1 circuit cuts out several steps of this otherwise complicated process. Much like bulk mailing, where the customer does a lot of the pre-sorting before the mail leaves their office, T1 customers are in essence doing the same thing.
"Back in the day" There was no CID on T-1 UNLESS you had MCI. They had a standard and you could have ANI which is similar to CID."
Yes and no again. AT&T always had this service as well, in fact their 4ESS toll switches have had it since they were first brought into production.
The key is where the T1 circuit originates. If it originates in an end office, common sense would be to deliver nearly identical capacities with more features as a PRI.
Name delivery has been the issue. T1 circuits via toll offices have always been able to deliver number-only data, but not name data which is considered to be end-office information.
If the T1 is there for the true need for a T1 (direct connection to the long distance network for bulk savings), then the T1 originates in a toll (typically 4ESS) office. Toll switches don't hand down end-user features since mass calling customers really don't care about individual call information. They receive this data in bulk format from their provider anyway.
