(Telecompaper) US carriers AT&T, Sprint, T-Mobile, US Cellular and Verizon Wireless plan to make it easier for consumers to unlock their mobile phones for use on a competitor's network. Industry group CTIA announced the voluntary agreement which will form part of the CTIA industry code of conduct. The announcement comes at the prompting of the new FCC chairman, Tom Wheeler, who last month said the service should be in place by Christmas. The CTIA announced six principles the operators will adopt in offering the service, half of which will be implemented within three months and the remainder within 12 months. Postpaid customers will be able to unlock their phones after completing their subscription contract or phone payments, and prepaid users can unlock the device after a year of service with the carrier. Customers will be notified when their devices become eligible for unlocking, and those who request the service will have their devices unlocked within two working days.