I'm currently trying out PortSIP SDK for iOS to make a VoIP App. I'm not familiar with this error, anyone have an idea what this means?
That error means "failed to create the network transport". Ensure the localSipPort which you passed into SDK which is not already used by other apps.
Try to test with portSIP parameters:
Account1: UserName:507 Password:507 SIPServer:portsip.net ServerPort:5060
Account2: UserName:508 Password:508 SIPServer:portsip.net ServerPort:5060