Depending on the software version of your CMS, the hardware platform, the size of your call center, & the number of outbound call records generated, you may be able to use the CMS to capture the date. The call record buffer is not that large. You can configure the CMS by changing the quantity of Call Records on the Data Storage Allocation table (under System Setup). The maximum appears to be 5000 records.
Other than that, the other choice woulld be a Call Detail Record (CDR) solution. eCAS (Avaya) is probably one of the better ones.
Kevin