The phrase "direct dial" means that you can call someone without having to go through an operator or any other person. You can simply dial their number directly and reach them. Full definition
All apartments provide the comfort and convenience of reverse cycle climate control, television, DVD players and direct dial phones with voice mail. (wikiaustralia.com)
Each guest room is featured with air conditioning, mini bar, international direct dial telephone, bathroom with amenities, hot and cold water, television and private terrace. (lakotour.com)
The guest room facilities include individual controlled air conditioning, mini bar, satellite television, hair dryer, bathroom with hot & cold shower, international direct dial telephone and private balcony. (lakotour.com)