SIP & VoIP utilities.

Small, focused tools for VoIP engineers. They run in your browser or your editor - no signup required. Pick the one that matches what you're trying to do.

• New

  Test numbers

  Free SIP/VoIP test phone numbers

  Dial-in test DIDs for VoIP engineers: caller-ID readback IVR, 1-second echo, milliwatt 1004 Hz, real-time DTMF playback, STIR/SHAKEN attestation readback, time announcement, and T.38 faxback.

  See the numbers

• Browser-side

  STIR/SHAKEN

  STIR/SHAKEN Identity decoder

  Paste a SIP Identity header (or share link) to decode the PASSporT, verify the certificate chain, and inspect Rich Call Data - RFC 8224 / 8225 / 8226 / ATIS-1000074 / RFC 9795.

  Open the decoder

• New

  DNS & TLS

  SIP DNS & TLS diagnostics

  RFC 3263 NAPTR/SRV/A walk with a 3-way consensus matrix across Sipflow, Cloudflare DoH, and Google DoH, plus sips TLS handshake with RFC 5922 §7.2 cert checks. Shareable links.

  Diagnose a target

• Browser-side

  WebRTC

  WebRTC diagnostics

  One-click browser and network readiness check: API support, media devices, codec detection, WSS SIP handshake, STUN/TURN ICE gather, and local audio loopback - all from your browser.

  Run diagnostics

• New

  Softphone

  WebRTC SIP softphone

  Browser dialer built on JsSIP. Multiple profiles, custom SIP headers, STUN/TURN, raw WebSocket log, live diagnostics, STIR/SHAKEN attestation badge, and one-click handoff into the SIP Flow analyzer. Everything stays on this device.

  Open the dialer

• New

  Fax over IP

  T.38 & T.30 fax decoder

  Drop a PCAP that carries fax: the analyzer classifies T.38 (UDPTL) or T.30 G.711 pass-through, surfaces failed reinvites (488 / 415 / 606), and decodes the pages to TIFF in your browser via spandsp compiled to WebAssembly.

  Decode a fax PCAP

• Browser-side

  IP Lookup

  IP & client diagnostics

  See your public IP with geolocation, ISP, ASN, and VPN/proxy/TOR signals. Includes browser, device, and connection details plus a Cloudflare-based speed test. Shareable links.

  Check your IP

• Editor

  MCP server

  Sipflow MCP - SIP & VoIP knowledge in your editor

  Hook Cursor, VS Code, Claude, or Codex CLI up to a curated VoIP knowledge base (Asterisk, FreeSWITCH, Kamailio, OpenSIPS, Twilio, Cisco, RFCs, STIR/SHAKEN) plus 20+ utilities: search, validate Identity, minimize a trace, detect the stack, and more.

  Install in seconds