The short answer
A message says a new version is required
Cisco retires old builds of the Webex app on a schedule. About a month before a build's end date the app starts prompting, and after it the app is blocked until it is upgraded. It is not a sign-in problem and nothing on our side needs changing.
The fix is a clean reinstall: uninstall Webex from Windows Add or Remove Programs (or drag it to the Trash on a Mac), download a fresh copy from webex.com/downloads, run it, and sign in with the same Apps Login. That download page is the only good source: an installer saved from an old email is itself out of date and reproduces the same block. Someone who cannot install software on the computer needs their own IT to run the installer.
Phone services keep disconnecting, or the app signs out and back in
The phone service side of Webex signs into one computer at a time. When the same login is open on a second office machine, a home computer left on, or a remote desktop session with its own copy of Webex, the two copies take the line from each other, which looks exactly like a bad connection. Sign out of the copy that is not in use. Over remote desktop, run Webex on the computer the headset is plugged into and sign out the other one. Phones and tablets never do this; only computers.
Sign-in never finishes, or Textdock says you are not an authorized user
This is a Webex account that was created for you but never finished on Cisco's side, and the cause is almost always a free Webex account that already exists on the same email address. Cisco will not finish the work account until the free one is cleared.
The fix is yours to do: sign in at webex.com with that email address, then delete the free account or move it to a different email address. Once it is off the address, the work account completes on its own and Textdock opens. No password reset helps here, because it is not a password problem.
Rings on the computer but not on the cell
The desktop app holds a live connection, so it rings the moment a call arrives. The mobile app does not while it is in the background; the phone has to wake it with a notification, and phones suppress notifications to save battery. Check three things on the phone: battery optimization for Webex set to Unrestricted (on a Samsung, also take Webex out of Sleeping apps), notifications on for Webex, and Do Not Disturb or Focus off.
For someone who takes calls on the go all day, the durable fix is Office Anywhere. It rings the cell number itself over the cellular network and does not depend on the app, the notification, or the battery settings at all.
Every call goes to voicemail while Webex shows you as available
The phone system's do not disturb does not sync with the app. Dial *79 from the app or any phone to turn it off. It is also on the extension's Settings tab in the portal.
Calls drop or go silent on the mobile app
A mobile app is only as good as the phone's connection at that moment: the location, the cellular signal, public Wi-Fi, a phone that put the app to sleep. When the same person's desktop app holds calls fine that day, the phone is the cause, and the fix is Office Anywhere rather than more app troubleshooting.
Nothing happens on a Chromebook
Webex on a Chromebook does messaging and meetings only. It does not make or take calls on a Vocatech extension. Use a desk phone, Office Anywhere, or both.
The activation email never came
Cisco sends the Webex activation email, not us, and we can ask Cisco to send it again. That request re-sends to everyone at your company who has not activated yet, not only the person who asked. The welcome email with the sign-in details is a different email, and we resend that one from the extension. See logins and passwords.