To the best of my knowledge:
As per definition given in Notification No. 12/2017 CT Rate dated 28.06.2017 (as amended)
(ze) “goods transport agency” means any person who provides service in relation to transport of goods by road and issues consignment note, by whatever name called;
Issuance of a consignment note is the necessary for a supplier of service to be considered as a Goods Transport Agency. If such a consignment note is not issued by the transporter, the service provider will not come within the ambit of goods transport agency
Individual truck/tempo operators who do not issue any consignment note are not covered within the meaning of the term GTA. As a corollary, the services provided by such individual transporters who do not issue a consignment note will be covered by the entry at s.no.18 of notification no.12/2017-CT (Rate), which is exempt from GST.
NOTE: Definition of Consignment Note is not given in GST Act or in Notification No 12/2017 CT Rate, but as per one flyer (https://www.cbic.gov.in/resources//htdocs-cbec/gst/goods_transport_service.pdf) we can take the meaning prescribed under the Explanation to Rule 4B of Service Tax Rules, 1994.
In terms of the said rule, consignment note means a document, issued by a goods transport agency against the receipt of goods for the purpose of transport of goods by road in a goods carriage, which is serially numbered, and contains the name of the consignor and consignee, registration number of the goods carriage in which the goods are transported, details of the goods transported, details of the place of origin and destination, person liable for paying service tax whether consignor, consignee or the goods transport agency.
Therefore in your case you are requested to check if the consignment note is issued and if it is issued then the same is subject to RCM under GTA service.
Other Experts/ Seniors are requested to correct me if there is any error in this post.