TLS SIP trunk via SBC...register line?

I’m running

I have an SBC which I do TLS to from my Asterisk. The SBC turns around and sends the traffic as UDP5060 towards the provider.
The SBC is at hostname_a and listens on port TLS/TCP 5062. The provider is at hostname_b and listens SIP/UDP 5060 (this host has a SRV record that is not reachable…but it does respond when Asterisk queries).

My register line is currently
tls://username@hostname_a:5062:password … hostname_b

Am I close? Right now it’s trying to do TCP 5062 to hostname_b.

THanks for any help