Some alters can communicate with each other; some cannot. This can be worked on over time, and therapy can be a great tool to assist with this communication. Some alters will communicate auditorially (hearing voices), some will speak out loud, some will write notes to one another, some will journal, some will share memories, some will communicate through loved ones. There are many ways alters find to communicate with one another. See DID/OSDD Survival Guide (System Communication Techniques) for more information.