my wife's iPhone goes to voicemail when I call

She has Do Not Disturb on, she has blocked your number, her phone has conditional forwarding turned on, she has a problem with her carrier, the phone is turned off? There are a lot of possibilities, but the issue is on her phone, not yours.

Interesting. What is it that you reset? Was it the Network settings, and was it on your phone or hers? If you reset the network settings, that cleared things for the cellular carrier, which is what you would found by contacting the carrier as I recommended. They also control voicemail, which could have meant there was a problem with the voicemail box. No matter, at least you got things going again.