Hi Adrian, first thanks for trying to help! Much appreciated! I did this for over a week in 1000 variants, even consulting gpt5 + claude for reviewing my prompt. Nonetheless when the Vapi Assistant listens to the users phone number AND if the user spells it in groups like "+one eleven....fifty five" it internally adds a "." at the end. When reading it back to the user, it spells "." behind the digit as either a date or "five, fifth". Spelling rules with "use digits 0-9 exlusively" , ignore "." etc. do not help at all. This is happening inside the formatting engine in Vapi and the is no chance to edit it. Only way I see to get rid of this issue - sounds crazy- is to have an external automation and clear the number string via function call and then read it back. I can´t believe this is the solution 🙂