ISP Information:
A Windows error message that is shown on a screen with a blue background. In Windows NT/2000/XP, this type of message causes the computer to stop completely, and is usually caused by improperly written hardware drivers or faulty hardware. Other BSODs can occur in different versions of Windows (95/98/Me) as well, but are not always as disastrous. Less frequently, black screens of death (also BSOD) are referred to as well
ISP Glossary:
BSOD - Stegozor wrote:Floyd L. Davidson a �crit: Reed wrote:Manish Bhasin wrote:I have a system where a modem is connected to a residential voipgateway using a two wire connection. This residential gateway istalking to an H323 - ISDN gateway over a satellite connection. Innormal voice calls I use G.729. But whenever there is a modem call,both the gateways upspeed to G.711 and I m using G711 A-Law right now.Disabling of Echo Cancellation in both the gateways is configurable(by default echo cancellation is disabled whenever there is a modemcall). I am using modems from a spanish manufacturer called SATELSAand need to make just the low data rate modems work (V.21, V.22,V.22bis, V.23)The problems is that...The call still fails....The average analog 2-wire dial modem has enough trouble workingover the channels for which they were designed to work. 3khzband-limited and all that. To try to operate them over a "lossy"medium like IP is going to be marginal and unreliable at best. Afew dropped or late packets and your done. ... I once had the opportunity to test Ayden ADPCM, Hughes DAMA, Scientific Atlanta DAMA, an AT&T packet system, and a couple of others, plus some older analog satellite equipment. (Basically everything available in Alaska in 2000.)...There's a solution for service providers from an Israeli company :http://www.surf-com.com/c6x.asp?section=3I'm certain that for for OEM's there are several similar solutionsavailable. However, it is unlikely that bulk providers will beopting to include all of that functionality until the technologyis significantly improved (smaller footprint and lower price).Any individual company that is building their own network, wherethe requirement will see high visibility for the functionalityneeded, however, might well want to include that into a design.(I would argue that it would be poor engineering to do so, andthat a fully digital solution, absent the modems, would be byfar preferred.)For now, I'd guess that the above list of systems that I workedwith (most of which were fairly old at that time) representswhat most customers will get from most bulk providers (ATT, forexample). Which is to say, virtually nothing! Both of the DAMA(Demand Assigned Multiple Access) systems mentioned aboveinclude optional plug in modules to provide the samefunctionality for FAX services only. Presumably modules arealso available for v.32 and v.34 modem protocols, but they werenot installed in the units I saw. Basically, the unit canprovide a 32 Kbps digital data channel, which for voice callsuses a form of ADPCM. When a FAX call is detected, it isdemodulated with the internal "modem" (the optional dsp module)and each end of the DAMA channel acts as a modem between thecallers modem and the destination modem, thus using the 32Kbpschannel as a digital channel rather than as a quasi-analogchannel (with its inherent SNR limitations that affect theanalog output of the modem).--FloydL. Davidson Ukpeagvik (Barrow, Alaska) floyd@barrow.com
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