Methods and apparatus to electronically tag a circuit pair are disclosed herein. Example methods include generating circuit identifying information to be included in a tag, transmitting the circuit identifying information to a first network element and to a portable circuit probe, and electronically tagging the circuit pair by applying a tone to the circuit pair at the first network element. In some examples, the tone is encoded to include the tag. Example methods additionally include notifying the portable circuit probe that the circuit pair has been electronically tagged. In some examples, the tag is transmitted to the first network element via the circuit pair and, if the first network element fails to acknowledge receipt of the circuit identifying information, via an out-of-band network.