Number | Name | Date | Kind |
---|---|---|---|
4677609 | Piereth et al. | Jun 1987 | |
4766604 | Axberg | Aug 1988 | |
4797910 | Daudelin | Jan 1989 | |
4805207 | McNutt et al. | Feb 1989 | |
4813070 | Humphreys et al. | Mar 1989 |
Entry |
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D. P. Worrall, "New Custom Calling Services,"Bell System Technical Journal, vol. 61, No. 5, May-June, 1982. |