No audible ring

I’ve got 2 polycom soundpoint 335 phones registered using the endpoint configuration manager.

I can make calls between the phones, however, they do not ring audibly. I’m having a very hard time figuring out how to configure a phone’s ringer.

When these phones are registered with a voip service provider, aptela, they ring fine.

The problem was the firmware revision on the phone was too old. I upgraded EPM to Then in EPM enable Polycom, enable 335, and install the 335 firmware. Configure the phone to point to FreePBX with protocol TFTP. When the phone booted freePBX pushed the new firmware to the phone. After several reboots the phone came up and worked correctly.