As an agent, you can manage your availability if you use the web app version of Be My Eyes. In the upper right corner of your browser window, you find your availability toggle bar. With this you can easily change your availability status, so you'll be marked as unavailable if you leave your work station. When you're marked as unavailable, calls will be redirected to your available colleagues. Just remember to switch back to available when you return.
For more information check out 'Managing your availability' article.