Groups
Use groups to organize endpoints within a test with different registrars, codecs, regions, and calling patterns for advanced SIP testing scenarios.
Groups are the mechanism for configuring different sets of endpoints within a single test. Each group can have its own registrar, media settings, assignment mode, and callee target. This lets you run complex, multi-configuration tests in a single execution with comparable conditions.
What Is a Group?
A group is a logical partition of endpoints within a test. All endpoints in a group share the same configuration:
- Registrar -- the SIP server they register with
- Audio codec -- the codec used for audio media
- Video settings -- codec, resolution, FPS (if enabled)
- Assignment mode -- which region or workers execute the endpoints
- Callee target -- who the endpoints call (external URI, another group, or receive external)
Every test has at least one group. When you create a test with a single group, all endpoints share the same configuration. When you add multiple groups, you can configure each independently while running them simultaneously under identical network and timing conditions.
Why Use Multiple Groups?
Single-group tests are sufficient for simple load testing. Multiple groups unlock advanced scenarios:
Compare Two SIP Servers
Test two SIP trunks or PBX systems side-by-side in the same run. Group A registers with Trunk A, Group B registers with Trunk B. Both groups run simultaneously, so any quality differences are attributable to the servers, not to timing or network conditions.
Compare Codecs
Test the same SIP server with different codecs. Group A uses PCMA (G.711), Group B uses Opus. Compare MOS, jitter, and packet loss to determine which codec delivers better quality on your infrastructure.
Test Cross-Group Calling
Simulate realistic call routing where one set of endpoints calls another set. Group A (callers) targets Group B (callees). This tests the full call flow through your SIP infrastructure, including call routing, codec negotiation, and media relay.
Test Geographic Distribution
Assign groups to different regions. Group A runs from US East workers, Group B from EU West workers. Both call the same SIP server to compare quality across geographic locations.
Mix Cloud and Custom Registrars
Group A uses the CallMeter cloud registrar for baseline measurement. Group B uses your production registrar. Compare quality to identify whether issues are in your infrastructure or in the network path.
Creating a Multi-Group Test
Step 1: Set Total Endpoints
In the global Configuration section, set the total endpoint count for the entire test. This is the combined count across all groups.
Step 2: Add Groups
Click Add Group to create additional groups beyond the default first group. The sidebar shows all groups with color-coded pills for quick navigation.
Step 3: Distribute Endpoints
Each group gets a percentage of the total endpoints. When you add or remove groups, the percentages rebalance automatically using a largest-remainder allocation method to ensure every endpoint is assigned.
Example distribution for 100 total endpoints:
| Groups | Distribution |
|---|---|
| 1 group | 100% (100 endpoints) |
| 2 groups (equal) | 50% / 50% (50 + 50 endpoints) |
| 2 groups (unequal) | 70% / 30% (70 + 30 endpoints) |
| 3 groups (equal) | 34% / 33% / 33% (34 + 33 + 33 endpoints) |
You can adjust each group's percentage using the slider in the group configuration panel. The percentages must always sum to 100%.
Minimum endpoints per group
Each group must have at least 2 endpoints (one caller and one callee) unless the group is configured to call an external URI or receive external calls, in which case a minimum of 1 endpoint is required.
Step 4: Configure Each Group
For each group, configure the following sections independently:
Connection Settings:
- Select a registrar (cloud or custom)
- Choose the callee target (external URI, another group, or receive external)
- Set the assignment mode (region or specific workers)
Media Settings:
- Choose audio mode (generic codecs or custom files)
- Optionally enable and configure video
Step 5: Review and Submit
The sidebar displays a summary of all groups, their endpoint counts, and their configurations. Review the summary and click Create Test.
Cross-Group Calling
One of the most powerful features of multi-group tests is cross-group calling, where endpoints in one group call endpoints in another group.
How It Works
- You configure Group A's callee setting to Target Another Group and select Group B
- When the test runs, endpoints in Group A act as callers and dial endpoints in Group B
- Group B endpoints register and wait for incoming calls from Group A
- Both sides exchange media and collect metrics independently
Requirements for Cross-Group Calling
- Both groups need SIP accounts on their respective registrars
- The calling group (Group A) and the receiving group (Group B) should have compatible endpoint counts
- Both registrars must be able to route calls between their registered users (either the same server or with proper trunk routing between them)
Practical Example: Testing a SIP Trunk
| Setting | Group A (Callers) | Group B (Callees) |
|---|---|---|
| Endpoints | 50 (50%) | 50 (50%) |
| Registrar | SIP Trunk Provider A | SIP Trunk Provider B |
| Callee | Target Group B | Receive from Group A |
| Audio | Opus | Opus |
| Region | US East | US East |
This configuration tests the call path from Provider A through your routing infrastructure to Provider B.
Real-World Scenarios
Scenario 1: Load Testing a PBX
You want to stress-test your Asterisk PBX with 200 concurrent calls.
- Groups: 1
- Endpoints: 400 (200 callers + 200 callees)
- Registrar: Your Asterisk server
- Audio: PCMU (matching your production codec)
- Buildup: 30 seconds to avoid registration storms
Scenario 2: Comparing Two SIP Trunks
You are evaluating two SIP trunk providers and want to compare call quality.
- Groups: 2
- Endpoints: 100 total (50 per group)
- Group A Registrar: Provider A
- Group B Registrar: Provider B
- Callee: Both groups call their own endpoints (intra-group)
- Audio: Same codec (PCMA) for fair comparison
- Region: Same region for both groups
After the test, compare MOS, jitter, and packet loss between the two groups in the results dashboard.
Scenario 3: Codec Quality Comparison
You want to compare audio quality across different codecs on the same SIP server.
- Groups: 3
- Endpoints: 60 total (20 per group)
- Registrar: Same registrar for all groups
- Group A Audio: PCMA
- Group B Audio: G.722
- Group C Audio: Opus
- Duration: 120 seconds for stable metrics
Scenario 4: Geographic Distribution Testing
You want to test how call quality varies by geographic location.
- Groups: 3
- Endpoints: 30 total (10 per group)
- Registrar: Same registrar for all groups
- Group A Region: US East
- Group B Region: EU West
- Group C Region: Asia Pacific
- Audio: Opus for all groups
Compare RTT, jitter, and MOS across regions to identify geographic quality differences.
Group Management Tips
- Name groups descriptively in the sidebar so you can identify them in results (e.g., "Trunk A - PCMA", "Trunk B - Opus")
- Keep groups comparable when doing A/B testing -- change only one variable at a time (codec, registrar, or region) for meaningful comparisons
- Watch SIP account counts -- each group needs enough accounts on its registrar. The form warns you if accounts are insufficient
- Plan endpoint distribution carefully -- more endpoints in a group produces more statistically significant results, but requires more SIP accounts and worker capacity
Next Steps
- Creating a Test -- Full test creation walkthrough
- Running a Test -- Execute your multi-group test
- Analyzing Results -- Filter and compare results by group
Creating a Test
Step-by-step guide to configuring a SIP load test with endpoints, groups, media settings, registrar selection, and assignment modes.
Advanced Track Settings
Configure DSCP/QoS marking for traffic prioritization and deferred track negotiation for mid-call media activation on a per-track basis.