Asterisk skype tls

Is it possible to register asterisk server with skype sip connect service using TLS? If yes how?

I have tried to use
register => tls://[USERNAME]:[PASSOWRD]
register => tls://[USERNAME]:[PASSOWRD]

Both of them does not work and I keep on getting below notice
chan_sip.c:15218 sip_reg_timeout: – Registration for ‘[username]’ timed out, trying again (Attempt #2)

CLI> sip show registry
Host dnsmgr Username Refresh State Reg.Time N [USERNAME] 120 Request Sent

If I try to register without using TLS, it just works fine
register => [USERNAME]:[PASSOWRD]

TLS on the asterisk server is working fine as I have been able to register phone using TLS/SRTP.