There are lots of technology to help with that:
1. Some companies link the phone number with the persons account that way reducing the verification time
2. Also by setting up clear categorisation before the client speaks to an agent, this can help direct customer to the most specialise agent.
3. Tracking the problems - sometimes clients are calling cause there is a problem that needs to be resolved, so by having a great system in place you can improve experience and reduce calls

I dont have much more context to share more