Extension within ring group when picked up getting dial tone

I have set up a ring group (601) that rings two extensions (7211, 7213) so far 7211 is the only one that is able to answer calls. Both phones ring however when extension 7213 is picked up all that is heard is dialtone. Please help. I have looked everywhere and so far found no solution.

Check to make sure you don’t have a codec compatibility issue. The call might be coming in as a g729 call and you may have a phone (such as a free soft phone) that does not have g729. Without a paid license, the call would be hung up.

I would have thought if it was codec outgoing calls should fail too from the extension that fails (7213) that extension is able to make outbound calls fine and when called directly answers fine. so I thought that maybe it shows as not available I tried *11 to make sure it is logged in. Any other thoughts