There is considerable code complexity in place for this ancient hack.
It dates back to 5ea1bc77a3
"
mgcp: Allow to freely control the a=fmtp line for experiments
In case of AMR one can specify the available codecs out-of-band. Allow
to configure this line statically in the configuration file.
"
Looking in mgcp_test.c output, the fmtp-extra tests do not even make
sense: they result in fmtp for pt=126 being added, even though there is
no payload type 126 listed in the SDP...
Related: OS#6313
Change-Id: Icee0cd1f5a751fa760d5a9deca29089e78e7eb93
Neels Hofmeyr
d0dbda4106