Spotify 0.7.x.xx doesn't work well in Chacha.
I found that upgrading Spotify to version 0.7.x.xx in HTC Chacha makes the music play with several pauses a second while the screen is off.
So it's advised not
to upgrade that app to that line of versions.
If you want to, you can find 0.6.7.220 version in this post
of the Spotify community.