Monday, August 06, 2012

One Device for both GSM or CDMA

Can you have one cellular device which works with AT&T, T-Mobile, Verizon, Sprint and others?  The answer is: Yes.

I have begun cellular tests of new units of Digi ConnectPort X4 and Digi TransPort WR21, both of which include a GOBI 3000 cellular module.  This means if I select AT&T and reboot, it 'converts' the radio to use AT&T compatible frequencies and firmware, while if I select Verizon or Sprint, it 'converts' to work with those networks.

Okay, what is the catch?
  1. Modest cost increase.  I'm not sure what, but the GOBI module requires a fairly large FLASH to hold multiple firmware images, plus special radio hardware.
  2. Slower reboots - so say some customers.  Since the cell module has more software-controlled hardware, it does take longer to start up.  I have not done any testing here, but eventually I will produce some numbers.
The carrier change goes surprising easy - one just selects AT&T, Verizon, Sprint (etc) on the mobile configuration web page and reboot.   That is it. 

Digi Support Documentation: Gobi 3G Cellular Carrier Conversion Guide

Digi is also working on a Python script which can be used with a 'test unit' activated on multiple networks (for example, the 3 big ones).  The script can be run for a few days and records various statistics - radio strength, connection delays, upload throughput.  This will be very useful for a customer with perhaps 100 sites to install, and they have reason to believe that no single carrier will be available at all 100 sites.