Dial Pad nonfunctional during phone call
Community--
I work at a restaurant that uses a phone program where it sends the calls to one of three manager's cell phones. Each time I answer a phone call, it requires me to press '1' to accept the call and speak to the customer. However, as of lately, I am unable to answer any of the calls, because each time I press '1' to accept the call, my phone does not register it. I have tried multiple times to hard reset my phone, and to no avail, has the situation been remedied.
Thank you all for your help.
iPhone 7, iOS 11.4.1