Problem: You're at your desktop PC, the N900 is in the next room. You hear a text message (SMS) coming in. In order to answer it, you have to get up and fetch the device. Even if the N900 is in your pocket, you need to change keyboards and type an answer on the small N900 when a full-sized desktop keyboard is right in front of you.

This shouldn't be necessary. There should be a mechanism to make ingoing text messages pop up on any of your computers and let you answer them right away, without ever touching the N900.

Use XMPP Link Lokal for Zeroconf Magic

On your desktop / laptop, run any instant messaging client that supports the "XMPP Serverless Messaging" protocol. AFAIK, such clients are available (and popular) for any major operating system.

A plug-in for serverless messaging is also available for Maemo 5.

This solution proposes to:

• Not do anything on the PC /laptop side except launch an IM client that supports Serverless Messaging.
• Write an application for Maemo that needs to be started whenever this feature is desired.
• The Maemo application will listen to incoming text messages. Once a new text message is detected, a temporary XMPP account is created that will be deleted again as soon as the application is closed. The temporary account uses the phone number the SMS originates from as its unique identifier and - if available - exposes the sender's name from the N900's contacts database over the XMPP-link.
• The application then sends the incoming text message to the PC via XMPP Serverless Messaging. Any answer coming from the PC to this temporary account will be sent back as SMS to the phone number that initiated the procedure.
• The user must define a list of PCs/accounts/networks that will be contacted by the application. IM clients that don't match an entry in this white list will not receive the contents of incoming text messages.
• The user can optionally tell the application to import all mobile phone numbers on startup and create temporary accounts for them. This way, SMS conversations to any known contact can be initiated from a PC.

Advantages

• No N900-specific client needed on the 'other side'. While some kind of client software is needed of course (any IM-software), it needn't be developed/ported/... for this special project.
• Standards-compliant; part of the infastructure ("People Nearby"-plugin) already in Extras.
• Relies on Telepathy, which is also used in MeeGo ==> future proof

Disadvantages

• Feasibility of proposed workflow uncertain.
• Potential unwanted side effects if, for example, sender of SMS shows up as "person nearby" on your girlfriend's laptop - even if she's not on the whitelist and doesn't get the text message itself.