Alex,
Be sure to call during office hours. They are closed on Tuesday and Wednesday.
As a word of advice, you’ll always find it easier to get a permit for a weekday (as long as it’s not a holiday).
Also, the updated number on their website is different from the one you’ve been calling. Here’s the skinny:
Office Hours:
May be closed for lunch between 12:00 pm – 1:00 pm
Monday 8:00 am – 3:00 pm
Tuesday/Wednesday closed
Thursday, Friday 8:00 am – 4:30 pm
Saturday, Sunday 7:00 am – 3:30 pm
Call ahead to inquire on the availability of Adventure and Interagency Passes, Wilderness Permits, and Forest Product Permits (909) 382-2882.