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Page 75
56 Kbps Modem Speeds
Disabling Call Waiting for Data Calls
?
Why can’t I achieve 56,000 bps data connections with my 56 Kbps modem?
! Current FCC restrictions limit modem communications to a maximum speed
of 53,000 bps over the public telephone network. However, even achieving
53,000 bps is difficult — if not impossible — to do on a consistent basis for
a number of reasons. First, the remote modem you call must also support a
top speed of 56,000 bps; otherwise, you are limited by the fastest speed
supported by the remote modem.
Even if the remote modem supports 56,000 bps, the signal amplifiers used on
some carrier lines reduce transmission speeds. You may want to check with
your local telephone company to see whether it uses such equipment.
If you dial through a PBX, the PBX may impose speed limitations that only
allow you to achieve top speeds in the low 40s. Maximum speeds are further
diminished when doing international dialing, which uses a signalling method
that reduces speeds to a maximum of 33,600 bps.
Another factor affecting connection speeds is the quality of the telephone
line. A telephone line that is prone to noise and other disturbances is less
likely to yield fast connection speeds than a clean line.
? If I connect my modem to a telephone line that has Call Waiting, is there any
way to turn off Call Waiting so it does not disconnect my data calls?
!
Call Waiting emits a beep to alert you that there is an incoming call when the
telephone line is in use. Although this beep is helpful for voice calls, it can
disconnect data calls made with your modem. You can deactivate Call
Waiting when originating a data call by adding the characters
*70 to the
beginning of the telephone number you want your modem to dial.
Alternatively, some types of communications software provide a checkbox
that lets you enable or disable Call Waiting. (Refer to your communications
software manual to see whether your software provides this feature.) Call
Waiting automatically reactivates at the end of the data call.