Do you know that during the early planning of toll-free (inbound paid) service there was no notion of using the 800 area code?
The plan was to use a special prefix within each area code—552 as I recall—to be toll free. It would be treated as a local call from within each area code exchange.
During customer focus sessions there was a concern from early potential customers that they would need a single nationwide number for advertising purposes. So the idea was modified to allow a national advertising company to purchase the same last four digits in every toll free prefix in every area code. Like clear frequency AM stations, certain thousands of banks would be reserved for national customers.
Eventually there was the realization that more national numbers would be needed than were going to be available in the 552 prefix.
So the idea transitioned to using a whole area code. That was filled with problems because it meant that every single call would need to be routed through a toll Center (Class 4 office.) It also meant that west coast users would need to dial 1+ even though the call was free. West coast users had learned that 1+ meant that there was a charge for the call. (Side note: it was never the intent that 1+ would be used for indicating a toll call. Dialing 1 first was done to route callers to long distance routing systems since step-x-step systems couldn’t handle ten digit dialing.)
When the 800 toll free area code was finally allocated there were still a number of hold overs from the original plan. For example, customers who didn’t need a nationwide number would be assigned the 800-552 prefix. The 800-552 prefix was assigned locally within each state, so an 800-552 phone number would be re-used in each state. Other prefixes were allocated to “regions” and were re-used in different regions. The idea that every 800 number would always be nationally-unique didn’t exist until about 1980, when a slow policy change was implemented.
The billing of 800 calls was crude, it worked. The billing systems run by each operating company were set so that the long distance rate was $0.00 per minute. The calls appeared initially on customer bills, but showed the $0.00 charge. This is because the local exchanges thought that EVERY area code was chargeable and they wrote the call out to the AMA or CAMA billing tapes. (Local central offices have never rated or priced calls.)
Then, a mechanical meter was wired to the inbound 800 number at the called customer end. These meters were manually read once a month. There was only a total number of minutes used…there could be no call detail because the called end had no idea of what the calling number was. (This was pre CCIS.) In fact, if an 800 customer lifted the phone and listened to dial tone they would be charged because the simple meter ran whenever the line was off hook.
Inbound 800 service was completely different from WATS, which was a flat rate outbound service. 800 Service (Initially called Zenith service, later renamed toll-free, and ultimately named 800 service) was an inbound only service. You could NOT place calls on your 800 line. And, separate physical phone lines were required for 800 service than for any other type of service. Early-on it was a common practice to reverse the tip and ring on 800 lines. This reversed the polarity and touch-tone phones at that time would not make tones when the polarity was reversed. It was a way to block customers from inadvertently using their 800 lines for outgoing calls, for which they would have been double-billed.