Can I use the Tracking System API service to obtain the longitude and latitude of my container vessel?

Of course. Tracking System API provides the vessel coordinates as well.

This is quite simple to accomplish. It is necessary to provide the following URL in the request URL: https://tracking.searates.com/route. 

Assume you want to find the location of the vessel that is carrying container CMAU1744423. Then the request URL should look like this: https://tracking.searates.com/route?type=CT&number=CMAU1744423&sealine=cmdu&ais=true&api_key=_your_api_key_