VoIP over VPN, works sometimes, can it be fixed?
VPN adds latency, fragmentation and an extra NAT layer. For occasional work-from-home it can do, but for production call-centre work VPN almost always causes audible degradation.
Try this first
- 1Test whether the phone also works without VPN (direct registration to SBC).
- 2If VPN is required: split-tunnel SIP/RTP outside the VPN.
- 3Lower VPN MTU to avoid fragmentation (1380-1400).
- 4For permanent home work: direct SIP registration with TLS/SRTP, no VPN.
When to bring us in
Security forbids direct internet registration: then a tested full-tunnel VPN with QoS, not 'let us try'.
See also
- Voys, BelXS or RoutIT, which cloud PBX fits?Three popular NL platforms, differences are admin UI, partner model and per-user price.
- Teams Phone: Calling Plan, Direct Routing or Operator Connect?Three ways to connect PSTN to Teams, cost and management differ a lot.
- 3CX: self-host on VPS or take 3CX cloud?Self-host saves licence, but you own SBC, backup and updates.
None of the above fits?
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