We uses the Router 3640 NM-2V IOSVersion 11.3(10)T with 8 FXOs Voice daughter card Hardware revision 1.1 at HQ. We uses the Router 2610 IOSVersion 11.3(10)T with 2 FXSs Voice daughter card Hardware revision 1.1 at Branch.Calls each other work just fine.
My problems are when I changed my branch router to Cisco 2811 ADVENTERPRISEK9-M, Version 12.4(11)XJ3 with VIC2-2FXS I can't call each other anymore.
When I call from FXO to FXS I got fast busy tone but I see 2 lines on FXS are idle state.
When I call from FXS to FXO I got unstable sound like Zaa..Zee..Zaa that no understanding I see lines on FXO are off-hook state.
Can be compatibility issues?
Thank in advance.