/conversations.join

{
    "channel": {
        "created": 1449252889,
        "creator": "U061F7AUR",
        "id": "C061EG9SL",
        "is_archived": false,
        "is_channel": true,
        "is_ext_shared": false,
        "is_general": true,
        "is_group": false,
        "is_im": false,
        "is_member": true,
        "is_mpim": false,
        "is_org_shared": false,
        "is_pending_ext_shared": false,
        "is_private": false,
        "is_shared": false,
        "name": "general",
        "name_normalized": "general",
        "pending_shared": [],
        "previous_names": [],
        "purpose": {
            "creator": "",
            "last_set": 0,
            "value": "For widget discussion"
        },
        "topic": {
            "creator": "",
            "last_set": 0,
            "value": "Which widget do you worry about?"
        },
        "unlinked": 0
    },
    "ok": true,
    "response_metadata": {
        "warnings": [
            "already_in_channel"
        ]
    },
    "warning": "already_in_channel"
}