Hi there,

Yes, 4.2(3) would be the minimum required version

DMA for Cisco Unified Communications Manager Release 4.x

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/compat/ccmcompmatr.html#wp57424

DMA release Notes

http://www.cisco.com/en/US/products/sw/voicesw/ps556/prod_release_notes_list.html

Data Migration Assistant (DMA) Release 7.1(3) collects application data from Unified CM Releases 4.1(3), 4.2(3), and 4.3(2) system for upgrade to Cisco Unified Communications Manager Release 7.1(3). DMA exports data in the current Window based system (with SQL server database) that later gets imported to the appliance-based system (with Informix database).

Cheers!

Rob