I use 8 of these to monitor my business and home. Not simple to set up, but quite a value once you get them working.
In a nutshell you need to use the included software to assign each one to a specific port of your router. In your router software you need to set up port forwarding so that port is open to outside traffic and is viewable from a remote location. Using a hosting service such as dyndns.org (which allows you one free host), or no-ip.org, you can view the port/camera from outside your network. Also if your IP is dynamic, which it commonly is, you need to install an update client that will update your IP to the hosting service as it shifts.
Paid hosting services start around $15/year. You can also subscribe to services that constantly record all video like a hard drive would. Update clients are free as well as port checker tools that verify that port is viewable from outside the network.
Note that one host name can view all the cameras, i.e., if your host is myname.dyndns.org, your cameras can be myname.dyndns,org:85 (port 85), then myname.dyndns.org:86 and so on.
Finally to view the cameras on your mobile device there are many apps available. I like Foscam Pro on my iPad and iPhone as it allows you to view the cameras within your network as well as outside. Many apps only allow viewing from outside your network. Foscam Pro also allows easy access to the camera settings which can be set to email you as well as record stills or video upon motion. Another nice feature is that the camera settings file can be emailed so that you don’t need to enter the same information on different devices. The software also has working sound (2-way), camera position presets, IR on/off, exposure/resolution control, and image flip/mirror for upright viewing regardless of mounting arrangement.
These are not a good substitute for a dedicated surveillance system with a hard drive, but great for live monitoring and checking on your home (or kids) while away. The video quality is acceptable, but the motion is often stop and go.
Sometimes power outages and general gremlins will mess with mine and reassigning a different port will get them working again. I’ve gone through the process enough that I can set up a new camera in 10 minutes.
As long as you don’t expect HD quality video and know the limitations of these cameras, they can be quite useful. Once you conquer the learning curve you will be pleased with the value and utility. $70 is a fair price and about what I bought mine for on Amazon some time ago.