All you need is to download the voxox dialer from voxox.com. Enter your profile details correctly. Verify your mobile number … they’ll send you sms code to be entered on screen.
and there you go with 120 free minutes along with free USA based incoming number.

Free minutes can be used via both application and sip adapter. However sip is officially not supported.

Settings for use of ipkall.com free Usa number with Pennytel.com
Account type: Sip
SIP Phone Number: 88xxxxxxxx
SIP Proxy: incoming.pennytel.com