The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 08, 2001
Filed:
Jan. 21, 1998
Francis A. Moody, Washington, DC (US);
Kyle D. McIntosh, Baltimore, MD (US);
Ciena Corporation, Linthicum, MD (US);
Abstract
To take advantage of 56K modem technology, a data signal must only traverse one digital to analog (D/A) conversion and one analog to digital (A/D) conversion on the return path to a subscriber. However, current data transmission for subscribers served by a Universal DLC system requires a D/A conversion at a voice switch of a public switched telephone network (PSTN), an A/D conversion at the central office terminal of a PSTN and a D/A conversion at a remote data terminal of a DLC system. This adds a D/A and an A/D conversion which causes 56K modem technology to fail. The present invention provides a telephone call routing apparatus installed between subscribers served by a Universal type digital loop carrier system, a central office terminal of a PSTN and a data network interface. The present invention avoids an additional digital to analog conversion performed at the PSTN voice switch and an additional analog to digital conversion performed at the PSTN central office terminal, thereby enabling 56K modem data transmission.