Solution:
Verify that the subscription provided by the Telco matches the configuration in the Perle.
The Network Protocol, SPID's, and Directory Numbers (DN) will be provided by the Telco.
The number one cause for the Perle not answering a call is a mismatch with the Directory Numbers configured in the Perle's BRI configuraton.
The Directory Number usually is the 10 digit telephone number for that circuit. Each BRI channel will have a unique DN, unless the Telco is sending a single DN most often in a Hunt Group.
In most case's if a Hunt Group is configured by the Telco, then configure ALL the Directory Numbers for each BRI channel in the Perle configuraton need to be the primary number Hunt Group number. You may need to verify with your Telco on what DN's they will send to the Perle.
Verify the board type in the Perle. You can view the board type by looking at the rear of the unit. Each board will have the type printed in the centre:
example: BRIU56E or BRIS56.
The "56" indicates that the card has the 56K analog modem support.
If the board does not have analog modem support you will see a message in the Event Log stating "no modem available".