Step 1. Go to Routing -> Agent Attributes on the top menu
Step 2. Click Add New Attribute
Step 3. Add attribute name: Multiple Work Numbers Enabled as screen shot below:
Step 4. Save Changes
Step 5. Go to User Accounts -> Edit Users on the top menu
Step 6. Click on Edit for the User
Step 7. Go to the Administrative tab
Step 8. Set Multiple Work Numbers Enabled to Yes
Step 9. Go to the Contact Info tab
Step 10. Click on Add Phone Number under the Work Phones section
Step 11. Add an additional number (Work 2) and click Save Changes