Pjsip over TCP and security

I would like to enable TCP support in order to have a native “background activity” with iPhone users (over UDP, the iOS client needs to workaround and keep the app alive without the iOS support, which eats the user’s battery, and this solution is less reliable).

Now, with TCP enabled on the client side, the registration failed.
I see that the Firewall module only specify 5160 over UDP and not TCP (Advanced > Port/Service Maps).

Other than creating a custom service, do I need to do anything else to enable TCP support? maybe something else not related to the security-side of it?
Is it even recommended or known as problematic?

Asterisk: 13.15.0

Many thanks!