Custom RIngtones for the Pantech C740 Matrix

Chop up your mp3 with Audacity then save it at a bitrate that gives you a final file size of 300k or less, next:

Can I assign different ringtones to each contact on Pantech Matrix?

Each contact that is stored in the Phone memory may be customized with individual ringtone and graphical caller ID, as well as storage of other contact information. All options for contacts stored in the SIM memory are limited and no personalized caller ID may be set.

Be aware that both SIM and Phone contacts will be displayed as there is no way to filter out one or the other. Unless you want each contact to show up twice, you should 'Menu > 8.Address Book > 1.Contacts > Options > 9.Copy & Move > 3.Copy All to Phone' then go again to 'Options' and then '10.Delete All > 2.SIM'