I have seen many “Agile teams” working quietly without talking to their teammates. Every day they are at work sharp 9 AM, pick up a user story from the backlog, finish it and go. Their interaction with other team members is limited. But each one is really happy as the are achieving something. This is where the line separating the “groups” and “teams gets blurred.
A team is a group of people who cannot work without depending on each other. That is, they have high interdependence on each other. However, a group need not have interdependence. A good example of a group is a call center. Typically in call centers, each attends the customer requests on their own and solves the problem. If one of the individual’s in the call center group is blocked with an issue, the rest are not affected. They could still continue working.
However, a team has shared the responsibility of delivery, and their work should be interdependent. In other words, team members have an agreed goal and the only way to achieve the goal is to work together. My thumb rule is, a user story cannot be moved to “Done” without the help of at least four other people :-)
I believe that if your team room is very quiet you might want to check if there is anything wrong there. You should ask why teams are not talking to each other ? do they have shared responsibility of work ? do they have a common goal to achieve or individual goals? How many people do you need to complete an user story?