There are a few possibilities why you lost dial tone. Here is a checklist of things you can check.

1. Make sure your internet is working. If you internet is not working your phone will not work because VoIP requires high speed internet in order to work.

2. Make sure the telephone is plugged into the appropriate port, Phone 1 or Phone 2.

3. Disconnect and re-connect the telephone cable between the adapter and telephone.

4. Power cycle your phone adapter by unplugging the power wait for 1 minute and plug the power back into the adapter.