Extensions and sub-accounts: free internal calling across your team

FreeVoIP is more than a single dialling identity — it is a full switchboard. You can create extensions using sub-accounts, each registered to its own ATA adapter, IP phone or softphone, and dial between them internally for free.

This is what turns a handful of Free SIP Accounts into a distributed office phone system: staff working from different homes or sites each register their own device, and calls between them travel VoIP-to-VoIP at no cost anywhere in the world. Because internal calls use short extension numbers rather than full phone numbers, day-to-day calling feels exactly like a traditional office PBX — but with nothing to install or maintain on site.