REP-001: Add ability to change (map) payload type (PT) of the RTP packets

[sobomax]

Overview

As it was pointed out by Carlos E. Wagner @kaduww, it would be useful to have an ability to change payload types of the packets. This is useful in particular with regards to the DTMF processing to resolve compatibility issues with certain UAs that cannot handle dynamic PT and expect DTMFs on a particular PT (e.g. 97).

Proposed Implementation

The original idea was to extend the catch_dtmf module allowing extra processing to be performed. However, upon further consideration it seems that since this task is not DTMF-specific it might be useful to have it implemented as a generic mapping functionality allowing specific PTs within the particular stream to be mapped to the other values regardless of the packet content.

As such, the implementation would entail creating a new module (rtp_proc ?) allowing number of mappings configured and applied on a per-stream basis.

[flaviogoncalves]

There are more info about the feature on https://docs.oracle.com/cd/E95618_01/html/sbc_scz810_acliconfiguration/GUID-36D4247F-2735-4498-916D-81EAA0B27C77.htm