Websites with free SIP account registrations. You can use such SIP account providers to e.g. test your is-phone softphone or to make calls over Wi-Fi connection with your iPhone and the is-phone softphone for iPhone (available in the iTunes App Store ).

• antiSIP  - English
• Call The World  - English
• ippi  - French
• i-p-tel  - German
• sipgate  - German
• sipcall  - German
• SIP2SIP (AG Projects)  - English
• VoIP User  - English