Abstract: A last number redial device which provides a valid dialing sequence/access code test, before the contents of a last number redial register are disturbed, is described. A first and a second register are alternately loaded with a first, threshold portion (N) of a telephone number (N+M) during a dialing sequence. The number of digits entered are counted. If the count is greater than a threshold amount (N+1), a toggle signal is produced indicating a valid number has been entered. A second, terminal portion of the telephone number produced during the dialing sequence is thereafter loaded to a third register. In this way, the entire number is loaded in the selected first or second register and the third register. If a last number redial sequence is initiated, the selected one of the first or second registers and the third register provide an output to the telephone line of the last dialed number.

Abstract: A last number redial device which provides a valid dialing sequence/access code test, before the contents of a last number redial register are disturbed, is described. A first and a second register are alternately loaded with a first, threshold portion (N) of a telephone number (N+M) during a dialing sequence. The number of digits entered are counted. If the count is greater than a threshold amount (N+1), a toggle signal is produced indicating a valid number has been entered. A second, terminal portion of the telephone number produced during the dialing sequence is thereafter loaded to a third register. In this way, the entire number is loaded in the selected first or second register and the third register. If a last number redial sequence is initiated, the selected one of the first or second registers and the third register provide an output to the telephone line of the last dialed number.