Conference call sending webex meeting email

[dsmutz]

User 1 is calling xxxx, connects call to user 2. Then tries to conference in user 3. When pressing conference, user 1 gets and email saying they are invited to webex and the call is disconnected. Why is this happening? All users are using a desk phone. User 1 & 3 only have desk phones. User 2 also has Webex soft phone but was not using it, was trying to answer call on desk phone. 

here is the email content:

[dtibbe]

Are you having a conference via Webex Calling or via Calls on Webex?

[dsmutz]

Neither. User 1 is using a desk phone with no Webex set up at all. She is calling others who have Webex soft phones available, but neither of them were using webex to answer user 1's call.