If the number is in your Twilio account or other service you’re using, and it’s active, you should be able to resolve that by clicking “sync” in your Call Center to sync the software and import your number.
If your number was deleted in Jensen, it will be deleted in Twilio as well. There is a 30 day window from when you delete the number in Twilio, to when you can pick it up again before another Twilio user is able to claim it. You would need to reach out to Twilio customer support and request for the decommissioned number to become active again and then import the number into Jensen.