In the past all 911 cell calls were routed through CHP but that's slowly beginning to change as now some calls are routed through Comm Center. I know SB County Fire is watching this post and I'm sure that information will be checked into.
Here's a posting I made in Dec 13, 05 that seems appropriate to repost:
Yesterday a few of us had the opportunity to visit the San Bernardino County Fire Communication Center. This facility better known as Comm. Center is where Wrightwood 911 calls are routed for emergency services.
The managers of Comm. Center asked that we pass on an alternate phone number to our forum visitors if you ever have issues connecting to a 911 call. Just remember that when you dial 911, from a standard phone line, your street address automatically pops up for the dispatcher. Cell phone locations are not known to the dispatcher when 911 is dialed.
The alternate 911 phone number for this area is: (909) 822-8071
Try 911 first!!