How to create a secure link to any iPhone

Hi I need my app to send a link to a customer to ask for their contact details to book an appointment. The problem I have is when I send the link to unknown iPhone it will not allow the link to work as I think it suspects the link to be spam. This will cause a real issue for my app as without this function I can see it working. Any help or advice would be appreciated please. Thanks Noel

How to create a secure link to any iPhone
 
 
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