At+t Corp.

Chi K Lam

Arvind S Chakravarti

Edward D Eng

Nancy Y Tai

Henry H Shen

Yuk-Ming Lam

A call-back service is disclosed having reduced post-dial delay. When a caller (12) initiates dialing of an international number of a called party (14), a dialer (28) monitors the dialed digits. Upon detecting a code corresponding to an international number, the dialer immediately launches a call to a node (16) in the caller's local exchange (18) while retaining the digits dialed by the calling party. The node then signals a call-back service platform (24) in a call back-country via a frame relay link (22) to launch a call through an ISDN network (26) back to the dialer. Thereafter, the dialer sends the digits to the call-back service platform which then launches a second call to the called party. The first and second calls are then bridged. By launching the call from the dialer upon detecting an international code in the number dialed by the calling party, the post dial delay is reduced.

International call back technique with reduced post dialing delay

A telephone call on a remote line (190) is initiated by establishing a simultaneous voice and data connection with a slave processor (180) tied to the remote line. The slave processor is responsive to commands received on the data connection, including an off hook command signaling the slave processor to go off-hook on both the voice connection and remote line. Thereafter, the slave processor (180) bridges the voice connection and remote line. Upon receipt of the digits of a telephone number entered on the voice connection, the slave processor, in turn will dial the digits on the remote line, thereby initiating a call on that line.

Method for initiating a telephone call on a remote line

A handshake between sending and receiving devices (10) that exchange DTMF signals across a network (14) is accomplished by having the receiving device send a DTMF ready tone (digit) for a prescribed interval following receipt of a call set-up message received after the sending device has initiated a call. Upon receipt of the DTMF ready digit, the sending device sends to the receiving device a data message includes a string of digits of interest prefixed by M header digits. After receiving at least a portion of the data message, the receiving device stops transmitting the ready digit. Once the receiving device has received the entire data message, the receiving device strips the protocol digits (the M header digits and any of the ready digits received due to echo). By analyzing the stripped protocol digits, the quality of the handshake between the receiving and sending devices can be determined.

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Morganville, NJ, United States of America

Chi K Lam