I have a problem with caller ID recognition with Asterisk during an incoming phone call, in fact sometimes Asterisk fails to get the caller number.
I am using a 2410 OpenVox card with DAHDI drivers to manage phone calls. When an incoming call arrives, the input audio contains some ring tones and the caller ID (encoded in FSK) between the first and the second ring tones. But if I start dahdi_monitor application to record the input audio I obtain a different audio than the incoming one. In fact, in this recorded audio, the FSK is partially overlapped with the second ring tone and so Asterisk CID recognition fails.
I am sure that the input audio (before entering the OpenVox card) is correct because I sniff it with another Windows PC mounting an acquisition card (ADC converter).
So I wonder why the DAHDI capture is different from the input one. Is there any configuration issue (Asterisk, DAHDI, …)? Is there something I can do to prevent this unwanted behavior?
You can see the images below to better understand the problem: