If bandwidth control is in use, there may be situations when
there is insufficient bandwidth available to place a call at
the requested rate. By default (and assuming that there is
some bandwidth still available) the VCS will still attempt to
connect the call, but at a reduced bandwidth – this is known as

downspeeding

Downspeeding can be configured so that it is applied in either or
both of the following scenarios:

when the requested bandwidth for the call exceeds the lowest

•

per-call

limit for the subzone or pipe(s)

when placing the call at the requested bandwidth would mean

•

that the

total

bandwidth limits for that subzone or pipe(s)

would be exceeded.

You can turn off downspeeding, in which case if there is
insufficient bandwidth to place the call at the originally
requested rate, the call will not be placed at all. This could be
used if, when your network is nearing capacity, you would rather
a call failed to connect at all than was connected at a lower
than requested speed. In this situation users will get one of the
following messages, depending on the message that initiated
the search:

Exceeds Call Capacity

•

Gatekeeper Resources Unavailable

•

About the Default Call Bandwidth

The default call bandwidth and downspeeding behavior are configured via:

VCS Configuration > Bandwidth > Configuration

•

You will be taken to the

Bandwidth Configuration

page.

xConfiguration Bandwidth Defaul

•

xConfiguration Bandwidth Downspee

•

Default call bandwidth (kbps)

Enter the bandwidth value to
be used for calls for which
no bandwidth value has been
specified by the system that
initiated the call.

Downspeed per call mode

Determines what will happen
if the

per-call

bandwidth

restrictions on a subzone
or pipe mean that there
is insufficient bandwidth
available to place a call at the
requested rate.

: the call will be

downspeeded.

Off

: the call will not be

placed.

Downspeed total mode

Determines what will happen if the

total

bandwidth restrictions on a subzone

or pipe mean that there is insufficient bandwidth available to place a call at the
requested rate.

: the call will be downspeeded.

Off

: the call will not be placed.

Save

Click here to save your changes

Usually, when a call is initiated the endpoint will include in the
request the amount of bandwidth it wishes to use. For those
cases where the endpoint has not specified the bandwidth, you
can set the VCS to apply a default bandwidth value.

This value cannot be
blank. The default
value is 384 kbps.

Configuring Default Call Bandwidth and Downspeeding

About Downspeeding