| 摘要 |
The present invention comprehends an improved ringing circuit particularly suitable for digital telecommunications systems wherein the energizing and de-energizing of the ring circuitry is programmably controlled to provide for either hardware or software generation of ringing cadence, dc bias polarity, dry-switching of ring relays, and other signaling voltages. Further in accordance with the invention, a digital implementation of a complete ringing circuit is achieved without the use of bulky transformers.
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