How to set time on Polycom IP 330

I am having issues with displaying the correct time on Polycom IP330 phones. Some of the phones show the correct date and time while others just show the flashing and incorrect time and date. Please advise.

Configure the SNTP server and possibly the IP gateway.

Menu | settings | advanced | password | Admin settings | Network Configuration | SNTP Address, GMT Offs. There are more on the web configuration page.