How many SIP trunk channels do I need?

Estimate the percentage of users expected to be on simultaneous external calls, multiply that by the number of users, then add a reasonable growth and safety reserve. Call patterns vary, so historical busy-hour data is preferable when available.

How much bandwidth does a SIP call use?

Bandwidth depends on the codec and network overhead. This calculator uses practical planning estimates of approximately 100 kbps per G.711 call, 40 kbps per G.729 call and 50 kbps per Opus call in each direction.

Should failover capacity equal primary SIP capacity?

For business-critical calling, the alternate PBX or destination should generally be able to handle the expected protected call load. Some organizations protect the full primary capacity; others protect only essential traffic.

Planning a SIP deployment or migration? Use the calculator freely, then send Triton the result for a practical engineering review. Start calculating →

Free SIP Capacity Planning Tool

How Many SIP Trunk Channels Does Your Business Need?

Estimate simultaneous calls, recommended SIP capacity, upload and download bandwidth, growth reserve and failover requirements for FreePBX, FusionPBX, 3CX, Asterisk and other compatible PBX platforms.

No Email Required Concurrent Calls Codec Bandwidth Growth Reserve HA Capacity

Calculate SIP Capacity → View SIP Pricing

Example Recommendation Live calculator

Recommended Capacity23concurrent calls with reserve

Expected Calls18

G.711 Bandwidth2.3 Mbps

Growth Reserve25%

Failover Capacity23 Calls

Primary PBX→Triton SIP→Alternate PBX

Channel EstimateConcurrent external calls

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Bandwidth EstimateUpload and download

Growth ReserveSafety margin included

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Failover PlanningProtected call capacity

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Instant ResultsNo form gate

SIP Trunk Calculator

Build a Practical Capacity Estimate.

Use busy-hour call records when available. Otherwise, choose the business profile that most closely matches your expected calling behavior and adjust the assumptions.

1Organization and call behaviorStart with users, locations and the expected calling profile.

Users or extensions Total people or extensions that may place or receive external calls. Business type Select a starting assumption, then adjust it below. Simultaneously calling

15%

Percentage of users expected on outside calls during the busiest period. Number of locations Used when suggesting regional and failover planning.

2Codec and network assumptionsBandwidth is estimated in each direction.

Codec Planning values include practical packet and transport overhead. Growth and safety allowance

25%

Add reserve for growth, unexpected peaks and call bursts. Do you need failover capacity?

StandardNo protected alternate destination Essential trafficProtect about 50% of capacity Full capacityAlternate destination matches primary

Next Step

Want an Engineer to Validate Your SIP Design?

Your calculator results are already attached to the request. Choose the next step and Triton will receive the recommended channels, bandwidth, growth reserve, locations and HA selection automatically.

Recommended capacity19 calls

Bandwidth / direction2.3 Mbps

Growth reserve25%

HA selectionNo failover selected

Explore High-Availability Options See SIP Trunking Pricing

No need to copy and paste your estimate. The current calculator results are included automatically.

How the Estimate Works

Three Steps Behind the Recommendation.

Estimate busy-hour calls

Users are multiplied by the expected simultaneous-calling percentage, unless a known peak is entered.

Add reserve capacity

The calculator adds fixed call paths and the selected growth allowance, then rounds up to a whole call path.

Calculate bandwidth

Recommended call capacity is multiplied by the selected codec estimate and network reserve in each direction.

Failover Capacity

Primary Capacity Is Only Half the Continuity Plan.

During a carrier, Internet, PBX or location failure, the alternate destination must be able to handle the traffic you intend to protect. Business-critical environments often reserve equivalent capacity at the alternate PBX.

Explore High Availability SIP → View Triton's Network

StandardOne primary destinationBest when brief interruption is acceptable.

2-Region HARegional alternate routingUseful for important business calling and multi-location operations.

3-Region HAMaximum Triton regional coverageDesigned for high-impact or geographically distributed environments.

Calculator FAQ

SIP Channels, Calls and Bandwidth.

These answers explain the assumptions behind the tool and when historical call data should replace general estimates.

Review Your Results →

Is one SIP channel the same as one concurrent call?

For most capacity-planning discussions, one active external call consumes one call path or channel. Transfers, conference bridges and forwarded calls can sometimes consume additional call legs, depending on the PBX and routing design.

Should I count internal extension-to-extension calls?

Normally, internal calls that remain inside the PBX do not consume a carrier SIP call path. Calls that leave the PBX, forward externally or bridge through external services may consume carrier capacity.

Why does the calculator use approximately 100 kbps for G.711?

The raw codec payload is lower, but practical network planning should include RTP, UDP, IP and link-layer overhead. Packetization and transport choices can change the actual result.

What concurrency percentage should I use?

Historical busy-hour data is best. Without it, general offices often start lower, while sales teams, support departments and call centers should use higher assumptions.

Does every location need its own bandwidth calculation?

Each site should have enough local Internet capacity for the calls that may originate or terminate there. A centralized PBX or SD-WAN design may change where voice traffic traverses the network.

Can Triton review the calculation?

Yes. Send the result along with PBX type, current call records, number count, locations and continuity goals for a more specific recommendation.

How do these channel estimates affect SIP cost?

Capacity affects how you compare channel-based and usage-based providers, but your total bill can also include call usage, DIDs, E911, Smart HA and other selected services. See Triton SIP trunking pricing →

Turn the Estimate Into a Real SIP Design.

Triton can review your PBX, busy-hour traffic, DIDs, locations, bandwidth and failover goals.

Run the Calculator → Talk to Engineering

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