MGCP chanel does support reverse polarity?

I’m working on Asterisk 13.8.2

I’m trying to send a reverse polarity message to the registered eMta so the eMTA can do the reverse polarity.

This is the message other call agents send to the eMTA to do the reverse polarity switch S:XAL/rev(-)

does anybody know if reverse polarity can be done in the mgcp module or at least confirm if there is something in the code to do that?