In a method for adding a caller to a group instant messaging chat, a computer receives an indication that the caller has joined a teleconference via a telephone call. The computer receives a characteristic of the telephone call. The computer determines that the received characteristic of the telephone call at least partially matches at least one stored characteristic of one or more invitees on a list of invitees to the teleconference. In response to determining that the received characteristic of the telephone call at least partially matches at least one stored characteristic of one or more invitees on a list of invitees to the teleconference, the computer requests an instant messaging server to add the caller to the group instant messaging chat.