What TRUNK SHORT and FILL Mean in VICIdial

On the VICIdial Real-Time Main Report you will see a pair of numbers labeled TRUNK SHORT/FILL. New operators tend to skip past them, but they are one of the clearest signals you have about whether your line capacity matches your dialing ambition. When connects feel slow or agents complain about idle time, this is one of the first places to look, because it tells you whether the bottleneck is leads, agents, or lines.

What SHORT means

SHORT is the first number. It counts how many calls the dialer wanted to place but could not, because there were not enough lines available on the servers dialing this Campaign. In other words, the pacing math said "place 12 calls now" but only 9 lines were free, so 3 calls went into the SHORT count. A SHORT that sits at zero means your Trunk capacity is comfortably ahead of demand. A SHORT that keeps climbing means you are line-constrained.

What FILL means

FILL is the second number. It counts how many lines on other dialers are being used to try to make up the shortfall. On a multi-server setup, VICIdial can borrow spare capacity elsewhere to keep the campaign fed. A healthy FILL means the system is covering for you. But if FILL is doing heavy lifting every day, that is a sign the campaign's own server is under-provisioned for the Dial level you are running.

flowchart TD
  A[Dialer wants N calls] --> B{Enough lines on this campaign servers?}
  B -- Yes --> C[Calls placed normally]
  B -- No --> D[Shortfall counts up SHORT]
  D --> E{Lines free on other dialers?}
  E -- Yes --> F[Borrow lines, FILL counts up]
  E -- No --> G[Calls stay unplaced]

What to do when SHORT is high

A persistently high SHORT means you are asking for more concurrent calls than your lines can carry. A few things to check:

• Dial level: an aggressive Predictive dialing ratio multiplies the calls demanded per agent. Lower it and SHORT should fall.
• Carrier capacity: confirm how many concurrent channels your carrier actually allows, then size your dialing to it.
• Server count: spreading agents across more dialers gives the pacing engine more lines to draw on.

It helps to think of SHORT and FILL as a supply-and-demand readout for lines, the same way the hopper figures are a supply-and-demand readout for leads. Demand is set by how many calls the pacing engine wants per second; supply is how many channels your carrier and your servers can carry at once. When demand outruns supply, SHORT records the gap and FILL records how much of it the wider system managed to cover from elsewhere. Neither number is a failure on its own, but their trend over a shift tells you whether to invest in lines or rein in pacing.

Watch SHORT and FILL alongside the calls-waiting counter and the agent rows. If SHORT is high but agents are still busy on calls, you may simply be at capacity for the moment and there is nothing to fix. If SHORT is high and a row of agents is sitting blue and waiting, you are leaving connects on the table because the dialer cannot get lines fast enough to feed them. That second case is the one worth chasing, and it usually resolves by adding lines or easing the pacing rather than touching the leads. For the full screen, see how to read the Real-Time Main Report, and the broader reports guide puts it in context.

Capacity that scales with you

If SHORT is forcing constant FILL, you may have outgrown your box. VICIfast spins up a right-sized managed VICIdial server in under 40 seconds. See our pricing to add capacity.