[asterisk-users] How does holdtime get calculated for queues

[Rob Hillis]

On 02/17/10 03:39, Warren Selby wrote:
> I had a customer ask me this question today, and I was surprised to
> say I didn't have an exact answer for them.  They have a relatively
> small support queue for their business (three agents, and rarely more
> than one person in line at any given time in the queue, if all agents
> are on a call),  Their support calls can range anywhere from 30
> seconds to 30 minutes.  Occasionally, they'll get four or five calls
> in a short time span, and the first three that are answered may end up
> being rather long.  The people in line are listening to hold music and
> hearing the periodic hold announcements and estimated wait times (you
> are currently caller number 2 in line, your estimated wait time is
> ....).  The complaint they're receiving is that the estimated hold
> time tends to jump around a bit - the example I was given was that a
> caller was told when they entered the queue, they were currently
> caller number 2 and the estimated hold time was less than 2 minutes. 
> The caller waited upwards of 10 minutes, and then hung up when the
> estimated wait time announcement told them the wait time was 8 more
> minutes.

I have a call centre that is very similar to yours - two or three
operators, normally minimal hold times with occasional busy times
(although in this case, it's when there's a special event on that the
volume of calls pick up rather than the length of each call) and found
that Asterisk's estimated hold time simply wasn't accurate enough.  In
my situation, I simply disabled the hold time and the complaints about
inaccurate wait times were replaced by lots of praise for the mere fact
that they were told "your call is number 3 in line".

The problem seems to be when Asterisk is used to long periods of next to
no waiting time - something you can't really fault Asterisk for since
it's not psychic.  I found that after 10 or 15 minutes and a half dozen
calls, the wait time became pretty accurate and stayed that way until
the queue emptied again.  It may be for the type of queues that we're
talking about here that trying to calculate hold times simply isn't
feasible.