Complex sentence: Originally to be introduced in 2015, on July 20,2011, the CRTC has moved up the introduction of the new 873 area code to September 15,2012 after a report stated that the current 819 area code would be exhausted by then.
Split into simpler sentences: Originally to be introduced in 2015, on July 20,2011, the CRTC has moved up the introduction of the new 873 area code to September 15,2012. The CRTC decided to move up the date, after a report stated that the current 819 area code would be exhausted by then.