Please can anyone help me with the codes on voice streaming of the following scenario...

I want to develop a code which can run on my PDAs making both of them to be able 2 communicate with each other over a network (the PDAs are wi-fi enabled)

Mode of communication is : 1. Voice calls
2. Text messaging

I intend to have a server (my laptop) which handles the whole of the switching process, and also is able to pass voice n data btw itself and the PDAs.

Have two personal digital assistants ( PDAs) and my laptop which connect to each other over a network.
I need to develop a code which will help stream voice and data over the network, making the PDAs able to make voice calls to each other and also to my laptop which also acts as the server or switching system here.

The laptop helps to switch calls btw both parties and also help to initiate an end to call btw both parties.
The laptop also runs both the client aand server software.

The switching should be fast and effective...Compression of voice over the network is allowed.