@lycho wrote Tried from two different receivers, same result.
It is not likely that trying a third handset will be any different.
Is it just one person that they are calling? Are they using their equipment to call your cell-phone?
After making a call from my cell phone and I press the number keys, the tones can be heard on their landline, just no voices either way.
That is strange. Are you calling their number, or a different number (such as Shaw Support: 1-888-472-2222) ?
The person (or business) that you call from your cell-phone should hear your voice and the tones from your phone's numeric pad. While you are talking through your cell-phone to "another" number, your parents should NOT hear anything through their telephone, unless you are calling their number.
As others may have said, disconnect the power-card from the Shaw Phone box, disconnect the coaxial-cable, and remove the battery from the Shaw Phone box. Wait a few seconds, and reconnect everything, and try again.
If you are in the same room as the parents, contact Shaw Support with your cell-phone, and hand your phone to a parent, so that the S.S. can diagnose the issue.
