From the manual
Poll
The TPI will respond with a Command Acknowledge code.
Note: The POLL command will also reset the Envisalink's network watchdog
timer. If there is no communications with the Envisalerts servers for a
period of 20 minutes, the Envisallink will reboot. Sending the TPI POLL
command will reset this timer. Useful if the module is not connected to the
Internet or firewalled.
Sounds like it does- this probably has more to do with the online service envisalink provides but it could be leveraged by a custom flow in node red if you don't want it to have internet access.
Does this code send a keep alive signal?
From the manual Poll The TPI will respond with a Command Acknowledge code. Note: The POLL command will also reset the Envisalink's network watchdog timer. If there is no communications with the Envisalerts servers for a period of 20 minutes, the Envisallink will reboot. Sending the TPI POLL command will reset this timer. Useful if the module is not connected to the Internet or firewalled.