Shane,
It's a bit hard for me to tell what default Method supports since I've customized my tables and screens, but I've confirmed that Quickbooks already has a field for Phone, Fax, E-mail, Alt. Phone, Alt Fax, and CC in the Customer table. If QB has the data, so will Method.
But, I cannot tell if the Method default configuration has these fields for the Invoice header. Mine does, but I've customized all my tables and screens. The Method Invoice screen does not have this field, nor does it retrieve this value from the Customer Record.
The steps to add this to the Invoice Header are pretty straightforward, but you'll need to make several customizations. Here's my recommendation about how to do this.
1. Export the Customer List table from Method to Excel using Method's Export Tool under the Integration Tools Tab of Customize. By looking at your data from QB as it is stored in Method you can get a very good understanding of which fields are holding which kind of data.
2. Do this also for the Invoice table.
3. Add the fields you need to the Invoice table. Try to use the same field names as the Customer Table as it will make your life easier down the line.
4. Customize the Invoice Screen to add the fields you need on the screen.
5. All of the customer specific information to an invoice is pulled from the Customer Table when you enter the customer name into the screen. You'll need to edit the Action Sequence tied to the Customer field of the default screen. You will see a bunch of statements that retrieve data from the Customer Table and then place the data into the active Invoice screen. You can copy one of these statements, move it into the same group and then modify it so that it retrieves your phone numbers, etc. and puts them into the invoice header.
6. You will then also need to add these fields to the Invoice report.
Of course, none of this will do you any good if you create an Invoice from a Sales Order since in that case the Invoice Header gets it's information from the Sales Order Header and not the Customer Table. In that case you'll need to also do all of the above to the Sales Order Screen and also modify the Create Invoice from Sales Order Screen to make sure this data get's copied from the Sales Order to the Invoice.
And, if you use the Estimates functionality, you will also need to do this to that screen as well.
It's a bit cumbersome, but for good reason. Whenever you create an Estimate, Sales Order, or Invoice you can pull all the Customer information from the Customer table, but you can also then modify that information for that specific Estimate, Sales Order, Invoice etc. Then you also want the system to copy that information from Estimate to Sales Order, from Sales Order to Invoice exactly as entered at any previous step. If, for some reason you select a new Customer or just reselect the same customer, any screen Estimate, Sales Order, or Invoice will pull in the customer data fresh from the Customer Table.
Clear as mud?