Tuning ViciDial Predictive Pacing: Dial Ratio, Abandon Rate, and Concurrency

How ViciDial Predictive Pacing Works

The predictive algorithm in ViciDial operates on a rolling window of recent call outcomes. It calculates:

• Expected answer rate: percentage of dials that result in a live connect in the recent window
• Expected handle time: average talk time per answered call
• Available agents: agents in a ready/waiting state right now

From these inputs it computes how many calls to dial simultaneously so that, statistically, a live agent is available when a call connects. The dial ratio (calls dialing ÷ available agents) is the primary output of this calculation.

The critical constraint: FTC rules require outbound abandon rate (calls answered by a live person but not connected to an agent within 2 seconds) to stay below 3% over a 30-day rolling window. ViciDial has an abandon rate field specifically for this cap. Set it; do not leave it at the default.

Step 1: Set the Abandon Rate Cap

In Admin → Campaigns → Campaign Detail:

• Max Abandon Ratio: Set to 3 (meaning 3%). This is the FTC Safe Harbor ceiling. Do not set it higher unless you have specific legal guidance for your campaign type.
• Abandon Rate Measurement Window: ViciDial calculates this as a running average. Campaigns with low call volume (under ~200 calls/day) will see high variance — do not rely on real-time abandon rate figures for small campaigns; look at the 7-day rolling figure.

Step 2: Configure the Dial Ratio

ViciDial uses two dial ratio settings:

Auto Dial Level: The starting dial ratio before the predictive algorithm accumulates enough data to self-tune. For a new campaign with unknown answer rates, start at 1.5 (1.5 calls per available agent). This is conservative enough to avoid an early abandon spike while the algorithm calibrates.

Max Dial Level: The ceiling the algorithm cannot exceed. For typical consumer outbound with 10–20% answer rates, a max of 3.0 is reasonable. For B2B campaigns with lower answer rates (4–8%), the algorithm needs a higher ceiling — up to 5.0 or 6.0 — to keep agents busy. Set the ceiling to match your expected answer rate environment, not a round number.

Adaptive Predictive Level: When set to Y, ViciDial adjusts the dial level automatically within the bounds above. Leave this on for predictive mode. Set to N only if you want manual fixed-ratio power dialing.

Step 3: Understand the Answer Rate Feedback Loop

The algorithm needs stable data to tune well. Instability sources to eliminate before trusting the auto-tune:

• List quality: Lists with large numbers of disconnected or fax numbers produce a noisy answer rate signal. Scrub lists before launch; do not use the predictive algorithm to discover list quality.
• Time-of-day variation: Answer rates shift significantly across the day. A campaign dialing through 8 AM–8 PM will see the algorithm oscillate between the morning low and midday high. Consider running separate campaign sessions per time block with different starting ratios.
• Agent availability spikes: When a large number of agents log out simultaneously (lunch break, shift change), the algorithm is temporarily working with stale agent counts. Build in a 2-minute ramp-down before shift breaks to prevent abandon spikes.

Step 4: Session-Level Capacity and Channel Planning

Predictive pacing assumes enough SIP channels to support the dial ratio. If your carrier or Asterisk is channel-constrained below what the algorithm wants to dial, the algorithm's output is artificially capped and agents starve.

The calculation:

`` Required channels = Max agents × Max dial ratio + buffer ``

For 50 agents at a 3.0 max dial ratio: 50 × 3.0 = 150 simultaneous call attempts, plus a 10–15% buffer for calls in ringing state beyond the average answer time. Plan for 165–175 concurrent SIP sessions.

On a flat-rate SIP network, concurrent session capacity is defined by your account tier — not per-minute cost. UnlimCall's per-seat pricing includes concurrent session capacity appropriate for predictive dialing workloads. See capacity planning for outbound call centers for the full concurrency model.

Step 5: Monitoring Pacing in Real Time

ViciDial's real-time monitor shows current dial level, calls in queue, agents waiting, and abandon count. Watch these during the first hour of a new campaign:

• Calls in queue rising: Dial level is too high; the algorithm is generating more connects than agents can handle. Temporarily lower Max Dial Level by 0.5 until the queue drains.
• Agents waiting > 0 consistently: Dial level is too low or answer rates are lower than the algorithm expected. Increase Auto Dial Level floor by 0.25 and monitor.
• Abandon rate > 2.5%: Back off Max Dial Level immediately. Do not wait until you hit 3%. Recovery from a 30-day rolling rate above 3% requires sustained below-3% performance for weeks.

Step 6: Flat-Rate Economics and Pacing Aggressiveness

On per-minute billing, operators face a perverse incentive: dialing more aggressively costs more money immediately. Many operators artificially suppress dial ratios to control telecom cost, which starves agents and reduces throughput.

On flat-rate billing at $99 per seat per month (US/CA), there is no marginal cost to dialing at 3.0 versus 1.5. The cost is fixed per seat. This removes the perverse incentive entirely — you can let the algorithm run at its optimal ratio without watching a per-minute meter tick up.

This is the structural argument for flat-rate SIP in predictive dialing environments. More aggressive pacing, same telecom cost, more talk time per agent, better economics per connected conversation. See flat-rate break-even math for outbound teams for the numbers.