The forum is available to all of Caldari Militia, not just the coalition, and allows people to communicate and work together more effectively. From ship fittings to military planning, the forum provides a centralized location for discussions to occur.
The Slack server is available for anyone in the CMC (CalMil Coalition) to use. Registration is done through SSO and is on a whitelist basis so only coalition members can join, and people that leave are pruned within 5-10 minutes. Due to the sensitive nature, Slack will remain a coalition only service.
The TeamSpeak server is available for anyone in Caldari Militia to use. It has no password so people can quickly hop on and work with public fleets, and supports API registration in order to get higher tiers of permissions to make more secure fleets.