Call going straight to Apple Watch voicemail

Hey s2529,

If you're having issues with phone calls routing to an old Apple Watch, it sounds like your iPhone might still be paired with it. The best thing to do is to erase and unpair all your Apple Watches and set yours back up again. For help with doing so, check out these resources:

Unpair and erase your Apple Watch - Apple Support

Set up your Apple Watch - Apple Support

• "Keep your Apple Watch and iPhone close together as you unpair them.
• Open the Apple Watch app on your iPhone.
• Go to the My Watch tab and tap All Watches.
• Tap the info button  next to the watch that you want to unpair. 
• Tap Unpair Apple Watch.
• For GPS + Cellular models, choose to keep or remove your cellular plan. 
  • If you want to pair your Apple Watch and iPhone again, keep your plan. 
  • If you don't want to pair your Apple Watch and iPhone again, remove your plan. If you aren't going to pair with a different watch or iPhone, you might need to contact your carrier to cancel your cellular subscription. 
• Tap again to confirm. You might need to enter your Apple ID password to disable Activation Lock. Before erasing all content and settings on your Apple Watch, your iPhone creates a new backup of your Apple Watch. You can use the backup to restore a new Apple Watch. After your Apple Watch unpairs, you'll see the Start Pairing message.
• Set up your Apple Watch again."

We hope this information helps out!

Take care.