Quoting Tilghman Lesher <tles...@digium.com>: > http://www.digchip.com/datasheets/parts/datasheet/222/82V2088-pdf.php > > See pages 17-18 of the associated PDF. While this is not the T1 framer chip > used, the values are identical, which leads me to believe that these values > are actually industry standard.
Well, maybe more like a defacto standard. But, it still doesn't explain when to use the different values in a software configuration, e.g. with Asterisk. As a term, DSX-1 is confusing. One description can be found in the Wikipedia article for T-carrier, which says it stands for Digital Signal Crossconnect: "DS1 signals are interconnected typically at Central Office locations at a common metallic cross-connect point known as a DSX-1. ..." On the other hand, articles like the following use DSX-1 to describe customer site connections: * Adtran NetVanta T1 Access Router http://www.arcelect.com/netvanta_access_t1_router.htm The diagram shows how two different NetVanta models can be used to connect a T-1 line to a PBX. There's also this page: * Primary Rate Interface ISDN Line Port http://www22.verizon.com/wholesale/solutions/solution/pri+rate+isdn.html Near the end, under Detailed Information, it says: "PRI service consists of a 4-wire DSX-1 port associated with a local switching system and the 4-wire DSX-1 cross-connect between the OTC DSX-1 termination and the local switching system DSX-1 termination. "PRI ports are DSX-1 interfaces that meet the electrical specifications in ANSI T1.102. PRI service and use B8ZS line code and the Extended Superframe Format (ESF) described in ANSI T1.403." Again, the term DSX-1 is used to describe a CPE port. In such cases, I think it will probably be appropriate to use the "DSX-1" column in the LBO table. Still, what's the difference between "CSU" and "DSX-1"?? Speculation: Could it be that "CSU" refers to situations where there is no equipment of any kind between the demarcation point and the ISDN card? In such cases, the ISDN card will have an integrated CSU, and the length of the cable will be unknown (thousands of feet), but you can know the attenuation value in dB; either by measuring it, or by getting it from the telco. This scenario may only occur in the United States. On the other hand, "DSX-1" will refer to situations where the ISDN card is connected -- via a DSX-1 port and a cable of a known length -- to an external CSU and/or DSU. In turn, this equipment is connected to the demarc. This scenario may apply in all other situations, e.g. ISDN BRI cards that connect to an NT-1. Does this sound reasonable? Thanks, Jaap -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users