Is it possible to use a SIP account with an iPhone? I know in 2009 jail broken iPhones had the ability to with a hacked application. Is this still the case? Thanks! EDIT: Finally found the info I was looking for: Acrobits: SIP VoIP for iOS Devices ACROBITS MOBILE VoIP SOLUTIONS The only ? I have: I will be using a Siemens Gigaset S675 IP system over Vonage, and need to find a SIP service. Anyone have any experience or knowledge? I've done this in E.U. which is more "advanced" with VoIP/SIP than the US and there is little knowledge online regarding SIP and US VoIP providers. Thanks again!