In some countries, such blocklisting is not customary. In 2012, major network companies in the United States, under government pressure, committed to introducing a blocklisting service, but it's not clear whether it will interoperate with the CEIR. GSM carriers AT&T and T-Mobile began blocking newly reported IMEIs in November 2012. Thefts reported prior to November 2012 were not added to the database. The CTIA refers users to websites at www.stolenphonechecker.org and the GSMA where consumers can check whether a smartphone has been reported as lost or stolen to its member carriers. The relationship between the former and any national or international IMEI blocklists is unclear.