All ground bonds for telephone and CATV should be bonded to the service entrance. In your case this would be the disconnect in the garage. The services should have been brought to this same location with the electric anyway for this reason.
If you can't locate the ground block in the garage then run a ground from the basement to the garage. If you say this is only ten feet you will be well within the 20 foot limitation.
Keep in mind that you do not have to land the ground on the bus in the panel. You can simply bug onto the grounding electrode conductor outside of the panel. As a matter of fact this is preferred since it keeps "unauthorized" people away from inside the panel.
-Hal
