It depends on your total channel lines and how many are allocated to outbound. In most setups, one outbound call uses two lines (agent leg + customer leg). If your default allocation is ⅔ outbound / ⅓ inbound, use the formula below.

Table of contents

• Key definitions
• Prerequisites
• Calculate your max parallel outbound calls
• Examples
• Verify your current capacity (step-by-step)
• Request a different outbound/inbound split
• Edge cases & limitations
• FAQ

Key definitions

• Channel line (line): A single call path. One live call uses one line per call leg.
• Two-leg outbound: The system bridges your agent leg and the customer leg → ~2 lines per outbound call.
• Allocation ratio: The proportion of your total lines earmarked for outbound vs. inbound (e.g., ⅔ outbound / ⅓ inbound by default).

Prerequisites

• Role: Admin/Billing or equivalent to view plan limits and request changes.
• Know your numbers: Total channel lines on your plan and the current outbound/inbound split.
• Access: Dashboard → Analytics/Usage and System/Call Logs.

Calculate your max parallel outbound calls

Formula (two-leg default):

Max parallel outbound = (Total lines × Outbound allocation) ÷ 2

• With default allocation ⅔ outbound:

Max = (Total lines × 2/3) ÷ 2

If your organization uses direct trunking without an agent leg, your account team can confirm if your setup uses ~1 line per outbound call instead. Adjust the divisor accordingly.

Examples

• 12 total lines → Outbound pool = 12 × ⅔ = 8 → 8 ÷ 2 = 4 parallel outbound calls.
• 15 total lines → Outbound pool = 15 × ⅔ = 10 → 10 ÷ 2 = 5 parallel outbound calls.
• All lines to outbound (no inbound) → Outbound pool = Total lines → Total ÷ 2 (two-leg).

Planning tip: Keep 10–20% headroom for transfers/conferences/recording to avoid unexpected blocks.

Verify your current capacity (step-by-step)

1. Open Dashboard → Analytics/Usage.
2. Find Concurrent Calls / Line Utilization and note Total lines and peak outbound concurrency.
3. Open Settings → Plan & Billing (or Account → Plan) to confirm total lines and any allocation policy.
4. (If needed) Check System Logs → Lost Calls to ensure inbound isn’t starved during campaigns.

Success check: Your observed peak outbound never exceeds the computed max; inbound remains available (unless intentionally disabled).

Edge cases & limitations

• Transfers/conferences: Briefly consume additional lines, reducing available outbound concurrency.
• Recordings & wrap-up: Processing may hold a line for a few seconds after hang-up.
• Queue/IVR occupancy: Inbound queuing uses lines; high inbound load can limit outbound.
• Dialer throttle: Auto-dialers may initiate multiple legs—cap concurrent dials below your maximum.
• Carrier restrictions: Some routes may fail despite capacity; check Error codes in logs.

FAQ

Q: Can I convert all lines to outbound?
A: Yes. Request a 100% outbound split for a window or permanently. Be aware inbound will be missed.

Q: Why does one outbound call “use 2 lines”?
A: In a typical two-leg bridge, the system holds an agent leg and a customer leg simultaneously.

Q: How do I avoid starving inbound during a campaign?
A: Keep at least ⅓ of lines for inbound or enable overflow routing/callback.