A switch for a telephony system in which an automatic conferencing service resides as a software module. To establish a conference call using the automatic conferencing service, an originating party dials a conference call access number. In response, the originating party receives a prompt tone indicating that phone numbers for a series of terminating parties for which participation in the conference call is desired. After entering a first phone number, the originating party selects an end of phone number delimiter. The originating party may then enter a next phone number or select an end of phone numbers entry delimiter. Upon detecting the end of phone numbers entry delimiter, the automatic conferencing service will send a call request for each of the terminating parties for which phone numbers were provided, initiate a countdown a time-out period and apply ringback to the telephone of the originating party. Upon receiving an answer from a first one of the terminating parties prior to expiration of the time-out period, ringback is discontinued and a call between the originating party and the first one of the terminating parties is completing. If additional ones of the terminating parties answer the call request before expiration of the time-out period, the additional ones of the terminating parties are bridged to the call. Upon expiration of the time-out period, any of the terminating parties failing to answer the call request are released.