5.37.2.4. Class of Trunk Configuration 
- The following COT parameters have to be added to a COT for VC trunks:
- SPCM = compressed speech channel
- NLHT = no local hold tone, hold tone from remote system When VCM transit is activated,
there is a noise based on connection setup / connection release during the toggling
function. If the COT parameter NLHT is set the connection will not be
released.
CHANGE-COT:COTNO=<?>,COTREF=COTADD,COTPAR=SPCM&NLHT;
- It's only possible to compress voice connections. Therefore all trunks where the type
of the
connection (voice or data) is unknown or connected with an multiplexer have to be
marked
with the following COT parameter:
- VCMN = voice compression not
allowed
CHANGE-COT:COTNO=<?>,COTREF=COTADD,COTPAR=VCMN;
- VCMN = voice compression not
allowed