how far will the corrections reach between base and rover?
and will it work in any area with cell service?
Sorry for late reply.
The maximum distance between the rover and the base where you can get a fixed solution depends on many factors. First of all from GPS receivers. It's about 10 km for low-cost receivers like the Emlid Reach RS and about 35 km for professional receivers like the Trimble R10 or Javad Triumph. One of our users said that he gets a fixed solution at a distance of 50 km using Topcon equipment.
Other factors that may affect this distance are the configuration of the satellites at a given time and various interference that may affect the signal.
And Yes, you can use YouCORS service anywhere where there is access to the Internet.