IMO, the only system worth looking at is the Cuddelink system by Cuddeback. You can link up to 15 cameras by radio frequency 1/4 mile or more apart depending on terrain without using or requiring a cell signal and have them send photos to a home camera in an easily checked location or if you are close enough you can link the home camera to your PC. Additionally you can link a Cuddeback Cell camera in as the home camera, place it in a spot where you have a good cell signal and have it forward photos to your phone from itself and the other 15 cameras. Cell plans are about $15 per month for up to 1000 images. That way you only have to buy one cell plan to cover all 16 cameras.
The cell version hasn't quite been released yet but it will very soon. The Cuddelink cameras are already available and I have been using 3 this summer with good results.
Make sure it is with the right carrier.I know I have cell coverage in the required areas.
I've got a good buddy who is pretty high up in cuddyback. Talking to him is what has spearheaded this post.
I know I have cell coverage in the required areas.