GPS is great for asset tracking because it gives precise location. However, when GPS signal can not be fixed (i.e. in the subway or underground parking), this method does not work anymore. However, you can still define the location roughly – with GSM signals.
Exactly for this purpose we have added the feature which allows to use the information coming from tracking devices about the closest GSM base stations.
For example, SPT-10 tracker has $MGBLAC command, which gives ID and signal level for up to 7 closest base stations. Next, using the databases linking LBS and GPS data, NAVIXY Server provides the rough location of the asset.
$MSG:MGBLAC=3000000118,20130626095439,46692,0840,3088,-75, 0840,c83e,-97,0840,a11a,-105, 0840,a12e,-107,0840,cdb0,-111,0840, a5b8, -111 , 0840,a568,-103
Even the location will not be defined very precisely in this case, this information can help in many critical situations, i.e. related to such security issues as kidnapping prevention or finding stolen cars.