Except we still do have many different standards for the phone system. As an example the main codecs used for encoding voice today are μ-law (North America), A-

Except we still do have many different standards for the phone system. As an example the main codecs used for encoding voice today are μ-law (North America), A-law (Europe), GSM (2G/3G), AMR (3G/4G), iLBC (VoIP), G.729 (VoIP). That is just for voice, now imagine you are a phone company and want to send a call to another phone company. There must be so many different things you need to cooperate on to make it happen - billing, switching, physical connections, numbering, codecs, etc. Yes the actual protocols may be standardised, but the main part is cooperation. It's not standards we need, it's companies that are willing to cooperate and work together. None of the big tech companies want to do that now though. Everyone wants their own walled garden so they can say they have more users that X competitor. (I'd argue that XMPP is good enough, or with a few extensions could be made good enough, for a company who really wants to push open IM)