The telephone numbers were formed by random digits, thus permitting access to both listed and unlisted numbers.

In a separate development, ICN Pharmaceuticals said yesterday that while data on ribavirin, another antiviral drug, were being judged, it would ask the drug agency to permit its free distribution to large numbers of patients who show an early sign of AIDS infection but have not developed the fatal disorder.

Within each exchange, random digits were added to form a complete telephone number to permit access both to listed and unlisted numbers.

For each exchange, the final four numerals were formed by random digits, thus permitting access to both listed and unlisted numbers.