The February 2013 release of VolunteerRescue includes a new phone service.  This service can be used for both outgoing calls (e.g. to dispatch members for a task) and for incoming calls (e.g. to provide an information line).

The outgoing calls service will mainly be used for dispatching members at the start of a task, i.e. when your group receives a request for a response and you need to contact your members to inform them their help is requested and to see if they can actually attend.