The best alternatives to Doorport are Ring, Lockitron Bolt, and August Home. If these 3 options don't work for you, we've listed a few more alternatives below.
Ring products are based on a simple principle -- use your existing home Wi-Fi network to create a ring of security around your home. By hooking up to your Wi-Fi, Ring products use the free Ring app to alert you whenever someone approaches your door or comes in a range of a security camera. You can then view an HD video stream of the person and speak to them using two-way audio communication.