how to enter the phone number?

Hi all,we have a site with woocommerce set up as a product catalog so that customers cannot buy products but only contact if they are interested. The problem is that contact can only be made with the email visible but without the phone number, whereas my client would like it mandatory. We also have a generic contact form on the contact page and have included the mandatory phone, but often customers contact through the product page. So how can the mandatory phone be included? The plugin used is YITH Request a Quote for WooCommerce: by YITH – 2.17.0 . Thank you

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