VoIP and communication server workloads have distinct resource needs compared to typical web applications — heavily dependent on concurrent call/user count and real-time processing requirements. This guide covers realistic sizing.
The Key Factors Affecting Requirements
- Number of concurrent calls/participants
- Whether transcoding between codecs is needed
- Video vs audio-only communication
- Additional features active (call recording, IVR, conferencing)
Asterisk/FreePBX Sizing Guidance
| Concurrent Calls | Approximate Specs |
|---|---|
| Up to ~10 | 2 vCPU, 2-4 GB RAM |
| 10-50 | 4 vCPU, 4-8 GB RAM |
| 50+ | Consider dedicated resources and load testing your specific configuration |
These are rough estimates for audio-only calls without transcoding — recording, transcoding, or IVR-heavy call flows increase requirements meaningfully beyond these baseline figures.
Video Conferencing (Jitsi Meet) Sizing
Video is substantially more resource-intensive than audio — a single VPS running Jitsi Meet comfortably handles a limited number of concurrent participants; see How to Install a Self-Hosted Video Conferencing Server (Jitsi Meet) for specific baseline recommendations.
Chat/Messaging (Matrix/Synapse) Sizing
Generally lighter than voice/video workloads — a modest VPS (2 vCPU, 4 GB RAM) handles a reasonably active small-to-medium user base comfortably.
Bandwidth Requirements
See Understanding VoIP Codecs and Bandwidth Requirements for calculating expected bandwidth based on codec choice and concurrent call volume — often the more binding constraint than raw CPU/RAM for voice-only deployments.
Network Latency to Your VPS Matters
Unlike many workloads where latency is a secondary concern, real-time voice/video is highly latency-sensitive — choose a VPS location geographically close to your primary user base for the best call quality experience.
Disk I/O Considerations
If actively recording calls (see How to Set Up Call Recording and Compliance Logging), ensure adequate disk I/O performance and capacity — SSD storage is strongly recommended for any communication server workload with active recording.
Planning for Growth
Communication server usage often grows organically as a business scales — choose a VPS plan and provider allowing straightforward capacity increases rather than requiring a full migration when you outgrow initial sizing.
Testing Under Realistic Load
Before relying on any sizing estimate for a production deployment, test with realistic concurrent call/participant volume matching your actual expected usage — generic sizing guidance is a starting point, not a guarantee for your specific configuration and feature set.
Redundancy Considerations for Business-Critical Systems
For a business genuinely dependent on phone system uptime, consider whether a single VPS represents an unacceptable single point of failure, and whether redundant infrastructure (secondary server, multiple SIP trunk providers) is warranted for your risk tolerance.
Common Errors
Quality degrades specifically during peak concurrent usage — monitor actual resource usage during these periods (see How to Set Up Prometheus and Grafana for VPS Monitoring) to confirm whether you've genuinely outgrown current capacity.
Continue Reading
- Understanding VoIP Codecs and Bandwidth Requirements
- How to Install Asterisk PBX on a VPS
- How to Choose the Right VPS Plan for Your Workload
Browse more articles in VoIP & Communication Servers.
