The GoTenna Mesh Relay at Airport Road and Balmoral Drive, Huntsville, Alabama

What is it? It is a Bluetooth to 900 MHz relay sold by GoTenna allowing two cell phones without cell service to text each other directly through a 900 MHz spread-spectrum transceiver, or through another GoTenna relaying you when there is no cell phone service. Your otherwise unconnected cell phone connects through Bluetooth to the GoTenna Bluetooth/900 MHz. transceiver you carry with you through relays to another GoTenna equipped cell phone.

SMS Messages are not held by the relay for later, but those received when a live cell phone is in range will be sent in real time through the cellular network. (You must have GoTenna Plus.)

The GoTenna Mesh acting as a relay is powered at all times by battery and solar charger. It is 8 feet above ground inside my apartment and views a large clearing to the east. There are no tall buildings, but a few on the west are two story. Coverage is pretty regular for 0.6 to .7 mile. The range may be a mile or more in random places and on hills. For that reason, more relay nodes would increase coverage greatly. Please consider becoming a relay node to provide text communication by cell phone when the cell phone network is out.

Delivering a text message via SMS (You must have GoTenna Plus) : A received SMS message will not usually be held by the relay. SMS messages are relayed immediately when a live cell phone is near enough the relay to receive them. If others in the Huntsille area join in the mesh project and participation builds, I could see a dedicated telephone tied to the relay so anyone with a goTenna but without cell service can text any mobile phone. That depends on my having working cell service when the SMS message comes in.

Hint: A cell phone no longer connected to a provider can work with a goTenna. That is, if you can download the goTenna software and purchase the GoTenna Mesh. Apple Store will not allow downloads of apps via WiFi over deactivated phones. You must have service long enough to download the goTenna software.

The company Web site:  https://gotennamesh.com/

The company's worldwide mesh map: imeshyou.gotennamesh.com/

A typical forwarded SMS message has this header seen by the recipient:

"goTenna Network

Relay Message from (gid number)"

Note the sender will need to state his name or identity, and, it seems to me, suggest a way to reply or state no reply is possible.
The originating telephone number that displays will not be the goTenna equipped phone injecting the message, but the SMS relay used by the GoTenna system (software).

Some Technical Specifications for the GoTenna Mesh:
Power out .82 watts
Internal Antenna: 1.0 dBi peak gain
Data rate 2kbps
902-928 MHz band
51 channels
frequency-hopping spread spectrum, mode 2GFSK
The average time of occupancy on any frequency is not greater than 0.4 seconds within a 20 second period.

Official FCC Test data (PDF)