The technology to connect two (mobile) parties by voice or message has been solved a long time ago. Whether it's GSM, PCM, VOIP or whatever, it's all passe.
Messaging is even simpler.
What makes a solution useful is, not news, the network effect. Remember the old story about that super fax machine that can transmit a full color page in 0.01s and you are the only one with the glorious privilege of owning one? It's totally useless until you can find another person with the same machine. And its value increases proportionally, if not astronomically, with the number of people owning the same fax machine.
Part of the network effect is also the directory system. Besides having to be technically compatible, you need to know the address of the other party you want to talk to, when you need to. It is a joke if you have to frequently use another communication network in order to find out the number/address of the person to whom you want to communicate.
The only networks that are totally pervasive are plain old telephony (POTS) fixed and mobile and plain old SMS. The client apps for these services are available on every phone, with a globally universal addressing system run by the ITU. The only problem is that telcos like to fleece the maximum out of customers and customers feel better if they are able to get something for nothing.
SMS exploded in 1999 not just because the telcos finally made it affordable, but because every phone has an SMS client and SMS uses the same addressing as POTS. (MMS is dead despite every phone being fully equipped for it because telcos make it too expensive relative to its value.)
Today we have many contenders vying to replace mobile POTS and SMS. There is serious fragmentation. I have to install Viber, WhatsApp, a SIP VOIP client, Google Talk, Skype, Windows Live Messenger in order to network with the few people I know. Technically speaking they all perform the same job if you want to send/receive an instant message. Technically speaking they are all incompatible with one another. It's a nuisance.
Here's the low down:
|SMS||Viber||Talk||G+ Msgr||Live Msgr||Live Msgr PC||Skype|
|Cost||No||$0 1st year||Free|
*From the messaging service provider
WhatsApp and Viber use an ingenious method for directory. It attempts to use your MSISDN as your identifier and is successful for 99% of users out there.
From the table it is clear you cannot survive on one service for collaborative work, even if all your contacts use the same service. The best service for PCs is Windows Live Messenger. For mobiles it is split between Viber and Google Talk. From the people around me, it seems WhatsApp is more prevalent than Viber. Talk is automatically available to every Android phone but not many people may be aware it is there, or that they can add a second account if the account they use to register the phone is different from their daily Gmail account.
That, above, is the sad state of affairs. I don't even want to mention FaceBook. Because I am irritated by someone reporting he is eating curry at the moment.