calls going straight to voicemail?

[Dilbertian]

I'm awaiting a call back from a nurse. She's tried once already, but it went straight to voicemail. There is nothing in the missed calls log. My dc have just tested by phoning me, no problems. Could there be a setting that might be diverting the call? It's an iPhone SE 2020

Do you have unknown numbers set to voicemail?

What number is she calling from? Calls from local hospital number are number withheld. You may have withheld numbers blocked on your settings.