| Number | Name | Date | Kind |
|---|---|---|---|
| 4054756 | Comella et al. | Oct 1977 | |
| 4593157 | Usdan | Jun 1986 | |
| 4736405 | Akiyama | Apr 1988 | |
| 4763350 | Immendorfer et al. | Aug 1988 | |
| 4766604 | Axberg | Aug 1988 | |
| 4797910 | Daudelin | Jan 1989 | |
| 4825460 | Carter et al. | Apr 1989 |
| 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. |