CR2013 - Crosstab Column Issue - How to display a pre-specified list of columns?

Hi! I wasn't sure how to phrase the title.

I have a monthly cross tab report that contains a list of 800 Toll free numbers as the column headers, and the amount of calls that came in by date for the row. (Attached picture of a finished report).

Here's my dilemma: Our client would like to view the usage for every toll free that they have with us, even if there's no timestamp or CallsIn for that month. I have the record selection set up to pull all records matching those toll free numbers, but of course Crystal won't include any records that have no data. The attached image should have 2-3 DNIS in between that did not have usage this month.

Is there a way that I can have Crystal Reports display the list of toll free numbers, and THEN look at the timestamp & callsIn fields? I've already ensured the 'suppress empty columns' box is not checked.

Here's my record selection formula, if it helps:
{iDNISStat.DNIS} in ["Array Of Toll Free #s Here"]  and {iDNISStat.Timestamp} in LastFullMonth

Cross Tab expert set up:
Columns: DNIS, Rows: timestamp, Summarize: CallsIn

Thank you!!
cr2013-Crosstab-DNIS-example.png