| Number | Name | Date | Kind |
|---|---|---|---|
| 5247591 | Baran | Sep 1993 | |
| 5260986 | Pershan | Nov 1993 | |
| 5513126 | Harkins et al. | Apr 1996 | |
| 5592541 | Fleischer, III et al. | Jan 1997 | |
| 5630060 | Tang et al. | May 1997 |
| Entry |
|---|
| "Subscriber Service Applications", http:/www.bostontechnology.com/ssa-vm.htm, date unknown. |