Problem comparing dates

We are a call center that uses the Noble Systems dialer. The database we use is their version of Informix and does not have a data type for date and time together. So I have a call_date field and a call_time field. I have an access database connected to this database to export files and run reports. I have been having problems trying to figure out how to select data from the database that is between a start date time and end date time on an access form.

In the example below call_date_time is a text field that I combined call_date and call_time into. I am not sure if somehow I can combine the call_date and call_time in the query itself instead. Comparing dates that are text does not seem to be working well for me. Any help would be greatly appreciated.

SELECT Count(*) AS sales, publication, service, addi_status
FROM cust_otherpapers
WHERE status='ES' call_date_time Between Forms!frmSalesRecordPrintout_New_v2!txtAltDateTime And Forms!frmSalesRecordPrintout_New_v2!txtAltEndDateT ime
GROUP BY publication, service, addi_status
ORDER BY addi_status;