If you are coming from the QuickBooks Desktop world, you or your clients may have looked up customers by their phone numbers through the CTRL-F or Advanced Search. You are now on QuickBooks Online and are frustrated that you don't have that ability anymore. We get it
You actually do, it's just in a different spot. So if you have a phone number but not a customer name associated with it, no problem!
Go to your Sales Menu - then your Customers Tab
You will see a search box to find a particular customer. It isn't only for the name, but you can type in the address or the phone number, and the name of the customer will appear for you to select.
Sometimes, the hardest part of moving to new software is to figure out how to do something differently that you've always done.