Be Able to Tag Custom Phone Numbers

Several doctor's offices have one fax number for the office and a separate one for records and/or billing. As of now, you can't pick which number you want to tag for your letters if one is named "records fax" or any custom value. It will only let you tag the one labeled fax. So if me records request letter is being faxed to the records department, it may have the office fax number on it and I have to change it manually. You should be able to tag these custom values or you should be able to make custom labels for all providers that can be tagged.