Duplication IP for CPE

We have problem about few customers, how have a problem with duplication of IP for CPE. Customers are our VoIP gateway that retrieves the address and then pin their router that gets After some time, the router restores and retrieves the address, making the conflict and notify customers that the phone does not work. I tried up to the CPE sounds but it does not work. Did you meet with such a thing?

Are you saying that your customer routers are being handed the IP address of your gateway from DHCP? Sounds like your DHCP server has problems

Routers and voip gateway recive Ip in CPE dhcp. Only CPE recive Ip in my DHCP