Date: Wed, 17 Oct 2001 20:21:51 +0200 From: Ignatios Souvatzis <is@netbsd.org> To: freebsd-isdn@freebsd.org Subject: Re: NetJet-S and DOV Message-ID: <20011017202151.B3144@beverly.kleinbus.org> In-Reply-To: <20011017140600.C21633@tmp.com.br>; from prallon@tmp.com.br on Wed, Oct 17, 2001 at 02:06:00PM -0200 References: <004301c155e1$8007ec50$020aa8c0@aims.private> <20011017140600.C21633@tmp.com.br>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Oct 17, 2001 at 02:06:00PM -0200, Sergio de Souza Prallon wrote: > > I wrote this driver for my personal use here in Brazil. Here, the ISDN > B-channels are 8-bit clean. If I understand Traverse's tech staff, DOV > consists in declare in the call-setup (in the D-channel) packet that > you want the B-channel to be Voice Capable instead of Data Capable. That > was because of diferent charge prices made by some of the Telcos. > Unfortunately, most of the terminal servers in use in Australia are Ascend > and they have a `feature' that if they receive a Voice call, they only > take 7 out of every 8 bits of the traffic (because Voice in America is > sampled with 7 bits) EVEN IF THEY CARRY HDLC FRAMED DATA. A Telco could even use some voice compression method behind your back and transmit 2 voice channels over one 64 kilobit/s link, if you declared you want to transmit voice.... But about the 7 of 8 bit part - the US use ulaw encoding - don't they? thats a 14 bit into 8 bit compression - you need an 8bit channel to transport it. Unless they are sampling it at 7 kHz sample rate, but famous US ISDN hardware, e.g. the audio chip used by (now ancient) SUN workstations, only supported 8 kHz 8-bit uLAW-encoding. Regards, -is To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20011017202151.B3144>