Kazoo [0] offers this as a config option on devices (which can represent SIP desk phones, soft phones, WebRTC endpoints, or call-forwarded cell phones): call_forward.require_keypress [1] There's a lot of re-inventing of telecom wheels required (if even possible) with TwiML (and clones).

[0] https://github.com/2600hz/kazoo [1] https://docs.2600hz.com/dev/applications/crossbar/doc/device...