Think of a river bed where a stream of water runs through it, the water has created a channel for the water to follow a specific course to a specific destination. A "channel" is like that, they direct energies through a specific course to a specific destination.
A medium (go-between) is someone who can channel some and not all, communication between the living world, and the world of spirits. Hope this helps you.
It refers to the techniques used to convey a message. It may be a conversation, letter, telephone call, radio or television program. The sender should choose a channel that suits his communication purpose, needs of the message and the needs of the receiver. The choice of channel, in fact, depends on the nature of the message and the relationship between the sender and the receiver
Urgency of a message is a primary factor in whether to use the written or spoken medium. The written medium is usually preferred when the message is long, technical or formal in nature, and when the message must be documented .The oral medium is effective when the message is urgent or personal or immediate feedback is of great importance.
Written media used inside the organization may be memos, reports, employee manuals, electronic bulletin boards, even internal faxes, policy statements and company magazines. Oral communication may take the form of staff-meetings, reports, face-to-face discussions, presentations, audiotapes, telephone chats, teleconferences or videotapes.
External written communication media may be letters, reports, telegrams, cablegrams, mail grams, faxes, post-cards, ads, brochures, catalogues, news releases and circulars etc. A person may communicate orally in face discussions, by telephone, or speak to groups in live presentations through teleconferences, video conferences or television.