Are you plugging the headset's base unit into the handset port or headset port. It sounds like you're plugging in through the headset port. Although it's counter-intutive you actually need to connect through the handset port. The base unit of the CS70 has a jack in the front to allow you to plug in the handset so you can still use it if you want. Once you're connected through the handset jack anytime you want to switch between the headset and the handset, just turn the headset off and the dialtone will move to the handset until you hang up. The speakerphone should work fine as well.

Also if you're able to hear and be heard on your headset there's no reason to do the reset.