directory of mobile phone user

I think the directory of mobile phone user must be prepared at the earliest. The reason is the mobile phone no. is often used as contact no. in various business transactions & other similar activities. As at present there is no official directory of mobile user (post-paid & prepaid), we often face difficulties in contacting a person if his/her mobile is switched off or changed. This is also required from legal point of view. Moreover unscrupulus people often give false mobile no. etc.
Thanks,
S. BANERJEE