Abstract: Modems having line verification circuitry for automatically advising that a direct distance dialed network has been connected between the communicating modems with the echo suppressors in the network disabled, is disclosed. The line verification circuitry is either identical for all modems or may be master/slave equipment. The line verification circuitry includes a first tone generator for emitting a unique tone for disablingthe echo suppressors in the telephone line. A communicating modem, upon receiving this unique tone activates a second tone generator that emits a different second tone which is not capable of disabling the echo suppressors but is capable of transmission through the telephone line when the echo suppressors are disabled. (63)disabling the at both modems respond to the first and second tones for automatically verifying the existence of the desired communication link.