How to use Polycom phones with the pbxnsip PBX

The PBX supports the SIP devices 300, 500 and 600 and their updated revisions 301, 501 and 601. We are using version 1.5.2, but probably also other versions work correctly.

Configuration

When you use the Polycom phones, be sure to use the version 1.3 or higher of the PBX. The previous versions were able to configure the phones, but for some strange reason they did not play a tone when a call came in.
In order to use the phones, you must somehow make the phones fetch their configuration from the PBX. In order to do this, you can go to menu settings/…/network configuration/server menu and there change the server type from ftp to tftp. Here you can also specify the address of the PBX. Alternatively, you can specify the tftp server address in DHCP. However, if you need to manually change the phone anyway, you can set it up there as well.
You can see in the log og the PBX what messages the Polycom phones sent back to the PBX (use log level 9 for this purpose). It contains a lot of interesting information what was going on during the automatic setup of the phones.

Supported features

The PBX uses the Call-Info headers for paging and provides the Alert-Info headers for indicating the ringing melody. Once that the configuration trouble is over, the phones are working nice.
Message-waiting also works, but again there is the problem of displaying that a message is waiting. The 500 and 600 models start blinking, but on the 300 you have to dig into the menus to actually see that you have a message waiting.