Freestate Raceway yesterday unveiled its new Tel-a-bet system, which allows a patron to call in a wager for a race from one of several clubhouse tables equipped with a phone.

Frank De Francis, president of Freestate, which opens Friday for a 58-racing day season, was on hand to help promote Friday night's inaugural running of the $116,000 Potomac Stakes for 2-year-old colts. The race, to be run in two 10-horse divisions worth $58,000 each, will be the richest in Maryland harness history.

Another $100,000 race, the Lady Baltimore for 2-year-old fillies, will be run Aug. 20.

Freestate will sport a new look and a new timetable. Paul Enten, an architect who has designed World's Fair pavilions in seven different countries, has added stained glass windows above the betting windows, and harness portraits behind the cashiers.

The new timetable features Sunday racing for the first time, with Tuesdays dark. De Francis said he expects the change in dates to increase significantly the track's daily handle, which in 1981 averaged $462,311.

Tel-a-betting, big-money stakes and Sunday racing are major steps for a track that three years ago went bankrupt and was foreclosed by the National Bank of Washington.

"We want to make harness racing the best it can be in Maryland," said De Francis, who purchased the track for nearly $6 million in 1980 and has been pouring money into it ever since.

"We see ourselves as competing in the entertainment industry, so it is important for us to give the track a proper ambience and style whereby people will come out and feel totally comfortable," he said.

De Francis, a 55-year-old attorney, seemed most proud of Tel-a-bet. Having deposited a minimum of $200 in an account, a bettor will be given a code name and be able to simply call to place his bets up to two minutes before post time.

Winnings will be credited to the bettor's account, which can be cashed in any time. De Francis calls it the ultimate in luxury for the harness enthusiast.

Meanwhile, among the entries in the Potomac are a three-horse Billy Haughton entry and a horse called George Allen, bred from harness racing's leading sire, Meadow Skipper, who will be trying to emulate his namesake's sports success.

Post time will be 7:30 each night, 1:30 on Sundays. Stifano Action Delayed

The Pennsylvania Racing Commission postponed a decision yesterday until later this week on whether to revoke the license of trainer Ray Stifano.

The commission had voted earlier to revoke Stifano's license because of a felony conviction for the receiving of stolen property 14 years ago. Because of the revocation, Stifano also was barred from Maryland tracks.

Stifano appealed that decision and last Friday won a court-ordered stay of the revocation, pending the outcome of an appeal to the Pennsylvania commission. Yesterday's postponement means that Stifano may continue to work as a trainer in Pennsylvania and Maryland.