77090123, that would do.

Call Twilio, wait six seconds, send John's number as DTMF, Twilio calls John.

So yes, tap John in the normal phone app, the whole thing happens automatically,

and you're ultimately speaking to John through Twilio.

Twilio supports receiving DTMF for exactly these sorts of IVR applications.

There's an even nicer variation.

I wouldn't necessarily alter every contact's main number.

You could give each contact an additional number labelled something like Twilio.

John Smith, mobile, 077090123, 0114xxxx, 077090123.

Then you retain John's genuine number for WhatsApp, messages, caller identification, etc.

But select the Twilio number when you want the recorded business route.

And because you're using dual SIM, the Twilio DISA access number can be configured

on the iPhone to always use SIM 1.

Incoming Twilio.