How to configure Asterisk with TLS

Hi Team,
I am currently able to run SIP calls over asterisk but now I need to encrypt SIP packets for which I need TLS support.

     So here I am to know how can I configure asterisk with TLS as a result of which SIP packets can be sent in an encrypted form. 
     I am using asterisk 1.4.17 release. 

    I will be glad if I get information regarding this, as this issue is blocking for us.

Thanks & Regards
Shivam Agarwal