edit listing contact form fields

Hi. I’m just trying to add phone field in single listing contact form. I can’t find where to do this.
Also, if add phone field is not possible I woukld like to change email field to phone, or at least edit the text of the Message… field to write there asking to user to enter his phone number. I can’t even find where to translate and change the Message… field. I’m using Loco Translate and I’ve searched this field and couldn’t find it.
Can you help me?

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