My sister is studying in France for a term. She has a tiny room in her hall with no phone line. She has her mobile, but it’s on an English contract so she has to pay a lot for incoming calls. Getting a PAYG SIM out of the French appears to be impossible. Luckily, she’s got WiFi. Unluckily our iChat audio chats all fail… So I put on Skype Skype which I know gets round many firewalls.

With SkypeOut and SkypeIn (allowing her to call out to regular phones and receive calls to a phone number) she now has a regular phone integrated into an IM package. The coolest thing about this is that although people call her on a London number, she can pick up the call wherever she has her iBook and a broadband connection.

Now this got me thinking. I don’t much like the Skype app, especially the fact you are stuck with its software and it is not interoperable with other networks. But I’m tempted by a portable landline, and the accessories that even let you use it with your regular phone. Fortunately Skype isn’t the only VoIP provider – others are comitted to interoperability. Sipgate is one such, and as with Skype you can get hardware into which you can plug in your regular phone. But (with the exception of gizmo) these just replace your phone – they don’t integrate into instant messaging. Don’t get me wrong – it’s still great to be able to use your fixed line wherever you have internet access, but frankly the software for OS X (x-lite or SJPhone) sucks on the UI front. The hardware is fiddly and still strictly for geeks.

So, I thought, this is where Apple should come in. There’s been all this fuss over the iTunes phone, and the possibility of an iPhone, but this is a crowded market with little room for innovation. But they’ve got everything they need to integrate a cool, easy to use product based around VoIP: software and hardware wise.

– Start with iChat. It may be a bit buggy as far as audio chatting goes, but it’s got the coolest user interface going.

– Now to .mac add the facility to buy a phone number and call credit for calling out, so you can iChat to regular phones, and they can call you.

– Take Airport Express and develop a handset that can plug into it (by adding an RJ11 socket or using the USB). Now you’ve got a complete phone system. Customise it for each member of the family: configure iChat to send calls only to certain Airport Express phones, and have a signature ring, so you know the audio invite is for you (already it’s better than a regular phone!)

– Add voicemail to iChat. And the ability to access it via .mac so you can get your voicemail anywere. Even better – let iChat sync voicemail to your iPod – so you can download your messages and listen to them on the move. Since your iPod has your contacts, you could record voice memos on the move to…and when you get back and sync with your Mac, have them forwarded to your buddy’s voicemail.

Now you’ve got a phone system that gives you a landline network at home, with free internet calls to other Apple/AIM users, integrated instant messaging and you can take it wherever you can take your laptop. Now let’s got back to the iPhone, because if you add a mobile in now you’re extending iChat to whever you are. You can be reached on your landline, on iChat, on the move… Of course, this is more problematic outside the US, where mobile calls generally cost more, but follow the model being used for Skype on 3G (essentially VoIP on your mobile) and your have a model that would allow Apple to revolutionise the way we use the phone.