Two SIP lines come with every Free SIP Account

A single Free SIP Account is not limited to one device. Every account includes two SIP lines out of the box, so you can register two devices at once against the same credentials — for example a desk phone at your workstation and a softphone on your mobile — and take a second call while the first is in progress.

If you need more concurrent lines, you can raise the limit yourself from My Account → My VoIP → Lines. This is the same place you go to download a pre-configured Windows softphone for any of your lines.

Businesses that regularly need many simultaneous calls across a team should look at the 25-Line SIP Account, which provides twenty-five concurrent channels on a single account under one flat monthly fee.