| Number | Name | Date | Kind |
|---|---|---|---|
| 4122308 | Weinberger et al. | Oct 1978 | |
| 4766604 | Axberg | Aug 1988 |
| Entry |
|---|
| OSSGR, vol. 3, "Feature Specific Documents"; Technical Ref. TSY-000271 FSD 85-01-0100 "Calling Card Service"--Published by Bell Communications Research--Revision #3 dated Mar., 1988. |
| OSSGR, vol. 3, "Feature Specific Documents"; Technical Ref. TSY-000271 FSD-85-01-0200 "Collect Billing"--Published by Bell Communications Research--Revision #3 dated Mar. 1988. |