Storm Over Warlock by Andre Norton

Shann had no answer from the transport, only the continuing hum of a contact still open between the dome and the control cabin miles above Warlock. The Terran breathed slowly, deeply, felt the claws of the Throg bite his flesh as his chest expanded. Then, as if a knife slashed, the hum of that contact was gone. He had time to know a small flash of triumph. He had done it; he had aroused suspicion in the transport.

When the Throg officer clicked to the alien manning the landing beam, Shann's exultation grew. The beetle-head must have accepted that cut in communication as normal; he was still expecting the Terran ship to drop neatly into his claws.