Satellite Phones in India
Bringing a satellite phone into India can lead to detention and / or arrest.  The ownership and operation of satellite communications systems and amateur radio equipment is strictly regulated in India.  Satellite phones have to either be purchased in India from an authorised distributor or can be imported into India after receiving permission from the Department of Telecommunications (DoT). Iridium and Thuraya satellite phones are illegal in India.

Following the Mumbai terror attacks in 2011, the Directorate General of Shipping (DGS) banned the use of Thuraya & Iridium satellite phones and infrastructure in 2012; restrictions were already in place in 2010, for similar reasons, under provisions in the Indian Telegraph Act.

Passengers importing satellite telephone as baggage shall be required to declare the same to the Customs on arrival at immigration and customs checkpoints. Circular No.37 / 2010-Customs states that "satellite phone declared to Customs shall be allowed clearance subject to production of permission for use from DoT, Government of India." (...) "Satellite phones imported for use in India without a valid permission of DoT may be detained and appropriate action in accordance with the law may be initiated."

Indian media reports mention that National Technical Research Organisation (NTRO) has capability to detect, intercept and record phone communications using land and satellite-based communications link monitoring systems.  Scientists at Indian Institutes of Technology (IIT) have cracked GEO-Mobile Radio Interface GMR-1 and GMR-2 encryption algorithms. NTRO and ISRO can access archived data from Technology Experiment Satellite (TES), Cartosat-2A and Cartosat-2B besides two Radar Imaging Satellites namely RISAT-1 & RISAT-2.

INMARSAT satellite phones are allowed in India, but you will need permission from the Department of Telecommunications (DoT).

Source: Wikiwand

Notice: Prohibition on Unauthorized Use of Satellite Phones in India

This is to inform all visitors to India including foreign nationals that bringing in or using satellite phones (e.g Thuraya, Iridium etc.) in India without prior permission / license from the relevant Indian authorities is prohibited under Indian law.

2) Any passenger carrying satellite phone/ phones via baggage is required to declare the same to Customs on arrival and produce permission for use from the concerned authority.

3) Any individual found to be in possession of an unauthorized satellite phone in India is liable to be prosecuted as per Indian law, and all unauthorized sets found in possession of the individual will be seized by Indian law enforcement agencies.

4) Visitors and tourists coming to India are advised to comply with Indian laws and not bring in or use satellite phones in India without obtaining specific permission / license in advance from the concerned authorities.

Source: Embassy of India