On Monday, September 14th, the FMCSA announced that there will be a postponement of the URS system that was to eliminate the use of MC#s effective October 23rd, 2015. The FMCSA has posted to their website that an updated implementation timeline will be posted to the Federal Register in October.
From the FMCSA website:
“FMCSA will publish a Federal Register Notice in October regarding a regulatory extension to provide sufficient time for the Agency to launch the new URS website and implement multiple provisions that were to be effective on October 23, 2015.”
https://www.fmcsa.dot.gov/registration/unified-registration-system