What one vCPU handles
- Asterisk / FreeSWITCH without transcoding: about 150 concurrent calls per core, the PBX just relays RTP. With G.711 ↔ G.729 transcoding 30–40, with Opus about 30: encoding audio is CPU-heavy.
- WireGuard: 500 Mbps and more per core; ChaCha20 is very fast.
- Mail needs little CPU but memory: ClamAV keeps its signatures in RAM (about 1.5–2 GB), Rspamd a few hundred MB more.
Bandwidth for VoIP
One G.711 call takes about 87 kbps each way with headers, G.729 about 31. 100 concurrent G.711 calls need roughly 9 Mbps symmetric, but stability matters more than speed: test the line with the VoIP quality test and get exact numbers from the bandwidth calculator.
Where to host it
A regular cloud VPS with a public IP suits a PBX or VPN: location and a stable network matter more than raw power. For mail pick a host that opens port 25 and lets you set a PTR. Before buying, check the delay to the data centre with our ping.