Have a phone number in a paragraph top of page shows white which is correct, further down in contact details shows as black (as configured) on desktop web browsers (Various)/Android phones - white/black shows correctly - On iPhone text shows as blue at both locations.
It’s because the iPhone knows it’s a phone number and automatically changes into a clickable link so that a call can be made without having to manually enter the phone number. To control it, you’ll need to adjust the link colour, but that might cause an issue with the colour of other links.