Police traced a land-line phone number of a PCO booth in Haridwar from where the ransom call was made but could not identify the caller.
"Wife of the missing jeweller received the ransom call on her cell phone on Monday which was made from Haridwar. We are trying to trace the caller and a team might be sent for this purpose," said a senior police official associated with the probe.
Her wife had lodged a missing complaint at Karol Bagh police station after Sampath failed to return and did not even call back to give information about his whereabouts.
Police has been little suspicious in its investigations as Sampath was learnt to be under heavy debts.
The ransom caller did not identify himself while claiming that he came across Sampath in Haridwar following which he abducted him and demanded Rs 50 lakh for his safe release. No more calls were received after that, he added.