...However, there is no alternative. Since MNP has been piloted in some areas, for users who have changed to another carrier, the mobile phone number prefix can no longer reflect its current carrier. According to the relevant documents of the MIIT, the voice call function is allowed in 145 / 147 / 149 prefixes, carriers can decide whether to provide voice call function according to the needs of their customers. At present, the 147 / 149 prefixes that support voice calls is available. Operated by China Transport Telecommunication & Information Center.