"Hutch has informed that they are suspending the service from the current customers from all circles until they obtain the approval of the licensor, department of telecom for this service," TRAI said in a statement.
The company has also stopped advertising the service and was withdrawing all promotional materials, including banners and brochures, from the market, it said.
Earlier, the company had launched PTT as a value-added service to their subscribers without obtaining prior approval of the licensor, TRAI said.
On the other hand, DoT had issued a one-month notice to Tatas questioning their PTT services and has asked them to explain why a penalty should not be imposed on them or even indicated that their licence could be cancelled.
Tatas had said that they were offering the PTT services under the Internet Service Providers licence.