Most of the mobile phones will be using random device address. So only it is changing each time.
Q) How can i read the advertisment packet received at the PSoC which is sent by the phones (peripheral) ? Do I have to make any custom service to read the advertisment packet?
No need for having a custom service for this. You can just get it from the scan response data packet received at central side.
Please refer our Central projects in our GitHub: https://github.com/cypresssemiconductorco/PSoC-4-BLE/tree/master/100_Projects_in_100_Days
Refer Day_10, Day_11 projects.
Thanks & Regards,