Telos Zephyr Xstream User Manual
Page 224

USER’S MANUAL
Section 11: THE WORKS – Detailed Menu Reference 212
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HOT TIP!
It is important to understand that the Transmit and Receive settings on two connected units 
may very well NOT match. This is because there are frequently times when it is appropriate 
to use a different coding mode coming versus going. 
The important thing to remember is that the local Transmit mode must be compatible with the 
Receive settings and capabilities of the far end unit. 
 Whereas the local Receive mode must be compatible with the Transmit settings of the far 
end unit. 
Bitrate: (56 kbps; 64 kbps)
This is the bit rate used on each ISDN channel.  This setting configures the codec section, and 
also tells the ISDN interface what rate call to place the call over the network.  If both channels 
are dialed between the same two codecs, the available bit rate would be double this rate (i.e. 
112 or 128 kbps) allowing the “Stereo” or “Mono 128” transmission modes. 
This parameter should be matched between the Zephyr Xstream and the far end codec. Since 
the network must accommodate the rate selected, it is important to drop the call and redial if 
this parameter is changed during a call. 
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IMPORTANT!
The Bitrate selection operates differently if the Interface selection in the third Tel screen is 
set to Ethernet or V.35 Single
.
For more about this option when used with those Interface selections see Appendix 6 (Special 
Operational Modes) 
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COMPATIBILITY TIP!
The Zephyr Xstream specifies the bit rate per channel. Since certain modes (i.e. stereo or 
mono-128) require two channels to operate, the total (aggregate) bit rate would be double the 
number displayed in these cases. 
This is important, as some other brands specify the total bit rate.
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ISDN TIP!
Since this parameter specifies the bit rate placed over the dial up data network, it is 
important to understand the following: In some areas, only 56kbps or 64kbps service is 
available. In addition, since different network paths (trunk groups) are frequently used for the 
two rates, there are times where one rate may provide more reliable connections than the 
other. 
In our experience, the only sure way to know if a connection given between to particular 
points will work is to try it, first at 64kbps, and then at 56kbps, if the higher rate fails to 
connect (or is unreliable). 
