Maemo 5 and Later: Go to the application installer, enable Extras, and download Dialcentral (Note: technically its still in extras-testing because people haven't been reviewing it)
Maemo 4.1 and Earlier: Add the Extras Repository and check the App Manager for DialCentral
Linux: .deb files
For the most up to date version check out git.
Discuss your issue on Maemo.Org Talk
Check out a list of helpful troubleshooting tips
File a bug report against Extras->Dialcentral
View existing bug reports