Microsoft's grand plan to eliminate phone numbers

I've been puzzling over transcripts of a couple of recent speeches by Microsoft Chairman Bill Gates where he discussed his vision for the end of phone numbers. But it wasn't until today, when I learned more about Microsoft's "Echoes" services platform for telcos that I began piecing together how Gates & Co. thinks Microsoft can do this.

This is from one transcript of an early May speech Gates gave in Japan:

"Right now the mobile phone, the desktop phone, the e-mail that you have on the PC, or instant messaging, these are all very different things, and the issues about how much of your information or your schedule, your current activity you share with people who communicate with you is not well designed.... By bringing together all of these kinds of communication, we can greatly simplify them. We can get rid of phone numbers, have it so when you say you want to contact someone, based on who you are and where that person is, they can decide whether to take the call or take a message about that, and so a great efficiency improvement that can be made there." (emphasis mine)

So how does Microsoft propose getting rid of phone numbers? Here's an overview, from the same source who originally tipped me on Echoes:

Starting with Echoes Wave 1 -- the first iteration of Microsoft's services platform for telco providers that is due out this summer -- Microsoft plans to synchronize contacts. In other words, Live Messenger contacts will appear in a mobile user's address book (if the carrier is using Echoes). The contacts will be synced via Windows Live Messenger, so duplicates are eliminated.

Messenger contacts will automatically appear in users' phone address book, so that even if they don't know one of their Live Messenger contact's phone number, they still will be able to call it. Numbers will be able to ring simultaneously on multiple devices/systems. On the flip side, Echoes will help ensure instant-messaging-to-SMS continuity. A user can send an IM to any mobile contact, and the contact can respond via a text message.

So what is it about Echoes that will enable this magic? This is the source's explanation:

1. Echoes will assign a local mobile number to each Windows Live contact

2. Via its Address Book sync capabilities, Echoes will push these new new contacts into any mobile phone (no client required)

3. The user will be able to compose an SMS or place a voice call to these contacts

4. Echoes will ensure text messages are delivered to Windows Live contacts as chat conversations, and replies will be sent back from Messenger as SMS

5. Voice calls can be connected through Echoes directly from the mobile to the Windows Live Messenger user’s PC

6. As the mobile user will appear always “online” to friends (using Echoes client emulation server), conversations also will be able to start from the Windows Live cloud, pushed to the mobile as SMS

So what do you think? Does Microsoft's plan sound workable? Is this something you'd want to use in the next year or two (which is when Microsoft is encouraging carriers to push the Echoes functionality out)?