What exactly is the problem here? L
A phone call?Just apologise and then get on with your life.
Maybe its just me but I am not sure what you mean by " caught us in a call". And unless she is an under age minor, since you are 21, I don't know what her father would be really upset about since she should be old enough to set her own standards as an adult. If she is a minor and you, as an adult, are trying to date her then you have bigger problems than her father.
What would you like us to say? you got there it's up to you to get out.