How many connections can a GPS satellite handle?

Do cellphones get the time via atomic clock signal (WWV) or GPS satellite signal?

• As everyone knows, cellphones set themselves and keep very accurate time. However, I'm still not sure HOW they get the time in the first place. I always thought cellphones picked up on the time signal broadcast by the atomic clock (WWV radio station) in Colorado, or a similar atomic clock elsewhere (for those not in the U.S.) But someone else recently suggested to me that cellphones used a signal being broadcast from a GPS satellite (or more than one; I don't actually know how many GPS satellites there are). Does anyone know conclusively whether cellphones set themselves by the atomic clock, or by GPS satellite? Thank you.

• Answer:

  Cell phones have had downloaded time since digital phones service started. Prior to that you had to set it. Digital service started before phones had GPS access. The time is set by the service provider. They probably receive their time from WWV. *