If you are one of the many iPhone users out there then you have likely been anxiously awaiting a readily available and easy to use iPhone SIP client. In fact, until recently, one of the big knocks on iPhone has been the relatively hard to find user friendly iPhone SIP applications. This scarcity has been due in large part due to Apple’s decision not to support voice over the Internet. Luckily, things are changing and iPhone SIP is becoming much more widely available.

So what’s the big deal and why do people want an iPhone SIP client anyway? SIP, or Session Initiation Protocol, is a multimedia conferencing protocol that allows you to make telephone calls over the Internet. It does a whole lot more than that but telephony is the big draw. iPhone SIP enables users to make telephone calls via wireless networks, as opposed to using valuable and costly telephone minutes. In other words, SIP allows you to make calls to virtually anywhere in the world without using talk time.

Until recently, there were few iPhone SIP applications that would enable you to take advantage of VoIP technology. In recent months, however, there have been a number of announcements made by large SIP vendors such as Skype introducing SIP tools that make VoIP (voice over Internet protocol) an real option for current iPhone users. This is what many iPhone proponents have been waiting for since up to now iPhone SIP was really just another item on the list of wanted apps.

So why has iPhone SIP been so long in coming? The answer to that question is easy. iPhone SIP has been slow in developing due to Apple’s restrictions on how it can work. Apple has limited SIP to use on wireless networks (wi-fi), as opposed to through cellular providers. This means that SIP clients such as Skype will only work if you are in the range of a wi-fi network. This limitation was put in place so that iPhone VoIP calling would not cannibalize AT&T’s revenue from regular wireless calls. No doubt AT&T’s concern about this issue was greatly justified but the limitation has brought a lot of frustration to iPHone users who have anxiously awaited high quality and reliable iPhone SIP client applications.

Apples block on iPhone SIP VoIP clients that work over a cellular data connection continue but iPhone SIP advocates can take heart now as there are even and iPhone SIP clients available in the official iPhone app store. Apple has finally opened its arms, if not its network, to developers who are working to catch up with development of SIP clients. There are now, at last, a number of SIP applications to choose from and users, while perhaps not having the all encompassing open access they had hoped for, do have good access to SIP technology now.

As competition between iPhone SIP apps has grown, so too has the ease of use. The iPhone SIP clients that are available today are far more user friendly than earlier derivations. This is great news for users and should be a leading indicator that there will continue to be improvement in iPhone SIP apps. It is likely that these advancements will continue and the iPhone SIP market will only get better for users. So, good news for all you iPhone users out there--SIP is finally here.