I am in charge of a group of about 30 software development experts and architects. While these people are co-located in the companies organization chart, they do not really feel as a team. This is due to their work enviroment:

1) The people are spread over eight locations, with a max. distance of about 1000km (this is Europe).

2) The people don't work as team but instead get called as single people (and sometimes small groups into projects for as long as the projects run.

3) Travelling is somewhat limited as this requires business reasons. Lot is done via phone.

Do you have ideas or suggestions on how I could make these people feeling part of a joint organization where they support others and get supported by others. So that they get to know their peers, build a network, informally exchange information? So that they generally get the feeling of having common ground and derive motivation and job satisfaction?