I have been out goat hu ting lately and I have had a Verizon iPhone and a ZOLEO.
Both have worked fine for sending messages to home and work. However, the iPhone only sends and receives the messages while you are connected. My phone will not upload old messages (I.e if someone sends me a message in the morning and I then connect in the afternoon). ZOLEO does send me the messages, even if they were sent while the device was off. Once I connect I get all my messages.
I will keep carrying the zoleo for that purpose.