Verifying your trunk with the built-in test numbers

After connecting a PBX or handset to the 25-Line account, use the FreeVoIP test numbers to confirm each part of the path works before you go live:

• 1-555-555-0911 — checks the Caller ID your trunk is presenting. Essential to confirm before relying on national rates.
• 4443 — echo/audio test to check two-way sound quality across the trunk and diagnose one-way audio (usually a NAT or RTP firewall issue).
• 4747 — DTMF test to confirm key presses pass correctly, which matters for callers navigating your IVR and queues.

Run all three from a phone registered through the trunk. If Caller ID is withheld or wrong, check that anonymisation is off and the correct DID is set as outbound Caller ID.