Analog recEive and transMit (E&M) signaling between the Cisco gateway voice trunk and the attached PBX trunk can take any of the three dial supervision signaling types, as long as the PBX, router and gateway match.
In addition, the E&M type and audio implementation configuration needs to be selected accordingly.
These are the four main parameters that define an analog E&M implementation:
E&M interface types and wiring arrangement (Type I through V)
Audio implementation (two wire and four wire)
Start dial supervision signaling (immediate, winkstart and delaystart)
Address signaling (Dual Tone Multifrequency [DTMF] and pulse)
The configuration of E&M on Cisco IOS Software gateways is similar across all platforms. The voice port configuration is very important.
To resolve this issue, configure these four criteria on the voice ports.