Symptom
Callers do not hear ringback tones when calling into Dialogic 2000 Media Gateways (DMG2000 Gateways) using a T1 WinkStart line ; only silence is heard.
Reason for the issue / Background
There are several ways to configure DMG2000 Gateways for T1-CAS to collect DID digits; CPID type 1 and CPID type 2 with auto answer. Below is the trace that shows an incoming call CAS signaling with DMG set to CPID type 2 auto answer.
...
From the incoming call signaled to answered, it only takes about 600ms. This is not enough time for the DMG2000 Gateway to send ringback tones. The ringback tones only occur before the call is answered.
Solution
Configure the DMG2000 Gateway to use CPID type 1 (auto answer only available for type 2).
Set Incoming Rings Before Answer to 2.
...