GSAT-12, the communication satellite built by ISRO, weighs about 1410 kg at lift-off. The satellite was successfully launched onboard PSLV-C17 on July 15, 2011 with a lift-off mass of 1410 kg. The satellite was designed for a mission life of 8 years and was placed at 83ºE longitude. GSAT-12 was configured to carry 12 Extended C-band transponders to meet the country's growing demand for transponders in a short turn-around-time. The 12 Extended C-band transponders of GSAT-12 will augment the capacity in the INSAT system for various communication services like Tele-education, Telemedicine and for Village Resource Centres (VRC).

GSAT-1 carrying three C-band transponders and one S-band transponder was launched on April 18, 2001 by GSLV-D1. GSAT-1 was used for conducting communication experiments like digital audio broadcast, internet services and compressed digital TV transmission. Several new spacecraft elements like improved reaction control thrusters, fast recovery star sensors and heat pipe radiator panels were also tested on this satellite.

GSAT-2 was a 2000 kg class experimental communication satellite onboard the second developmental test flight of India's Geosynchronous Satellite Launch Vehicle, GSLV-D2. The satellite carries four C-band transponders, two Ku-band transponders and a Mobile Satellite Service (MSS) payload operating in S-band and C-band for forward link and return link respectively. GSAT-2 also carries four scientific experimental payloads - Total Radiation Dose Monitor (TRDM), Surface Charge Monitor (SCM), Solar X-ray Spectrometer (SOXS) and Coherent Radio Beacon Experiment (CRABEX).

GSAT-3, known as EDUSAT was meant for distant class room education from school level to higher education. This was the first dedicated "Educational Satellite" that provide the country with satellite based two way communication to class room for delivering educational materials. This was a Geo-synchronous satellite developed on I-2K bus. GSAT-3 was co-located with METSAT(KALPANA-1) and INSAT-3C at 74o E longitude.

GSAT-4 was the nineteenth geo-stationary satellite of India built by ISRO and fourth in the GSAT series. GSAT-4 was basically an experimental satellite. However, GSAT-4 was not placed in orbit as GSLV-D3 could not complete the mission.

GSAT-5P was the fifth satellite launched in the GSAT series. It was an exclusive communication satellite to further augment the communication services currently provided by the Indian National Satellite (INSAT) System. Weighing 2310 kg at lift-off, GSAT-5P carried 24 Normal C-band and 12 Extended C-band transponders. However, GSAT-5P was not placed in orbit as GSLV-F06 could not complete the mission.

GSAT-7 was a multi-band satellite carrying payloads in UHF, S-band, C-band and Ku-band. The satellite employs the standard 2000 Kg class bus (I-2K) platform with a power handling capability of around 3000 W and lift-off mass of 2550 Kg. It was planned to be launched during the second half of 2013 and to be positioned at 74^oE. GSAT-7 was an advanced communication satellite built by ISRO to provide wide range of service spectrum from low bit rate voice to high bit rate data communication. GSAT-7 Communication payload was designed to provide communication capabilities to users over a wide oceanic region including the Indian land-mass. The payload configuration was compatible with I-2.5K bus of ISRO. The GSAT-7 payload design includes Multiband communication. The Indian Armed Forces in general and Indian Navy in particular got another shot in the arm on 29 Sep 13 when India's first dedicated defence satellite GSAT-7 was launched by the Ariane-5 launch vehicle of Arianespace, French Guiana. The multi-band communication satellite named "Rukmini" will help Navy keep an eye on the Indian Ocean region (IOR) spread across 2,000 nautical miles of an area. It would proovide real-time inputs to Indian Navy Ships, Submarines and Aircraft. Additionally, The Indian Army, too, will get vital inputs about over-the-land movements.

The "over-the-sea use" Rukmini, with UHF, S, Ku and C-band transponders, was followed by GSAT-7A with the IAF and Army sharing its "over-the-land use" bandwidth. Indian Space Research Organisation’s (ISRO) Geosynchronous Satellite Launch Vehicle (GSLV-F11) successfully launched the communication satellite GSAT-7A from the Satish Dhawan Space Centre (SDSC) in Sriharikota 19-December-2018. The GSLV-F11 lifted off from the Second Launch Pad at SDSC at 04:10 pm IST, carrying 2250 kg GSAT-7A and about 19 minutes later, injected GSAT-7A into a Geosynchronous Transfer Orbit (GTO) of 170.8 km x 39127 km which was very close to the intended orbit. GSAT-7A will substantially enhance the communication systems of the Indian Air Force.

GSAT-6 was a high power S-band communication satellite that will be co-located with GSAT-12, INSAT-4A and GSAT-10 at 83ºE. The satellite was configured around I-2K bus with a lift-off mass of 2200 kg. It was configured with CxS and SxC transponders. The S-band up and down links have high G/T and EIRP to be able to communicate with smaller ground terminals. This satellite will also provide a platform for developing technologies such as demonstration of large unfurlable antenna in satellites, handheld ground terminals and network management techniques that could be useful in future satellite based mobile communication applications. In its ninth flight (GSLV-D6) conducted August 27, 2015, India's Geosynchronous Satellite Launch Vehicle, equipped with the indigenous Cryogenic Upper Stage (CUS), successfully launched GSAT-6, GSAT-6 spacecraft was configured with five S-band beams to cover the Indian main land, each beam supporting one CxS-band forward link transponder and one SxC-Band return link transponder. Thus, the 5 beams will have paired five transponders. The communication link operates through a Hub. The spacecraft employs the standard I-2k has with a power generation capability of around 3.1 KW. The spacecraft weighs 2200 kg at lift-off. The payload uses a high power S-Band TWTA and a new technology 6m unfurlable antenna.

GSAT-6A was to be a follow-on satellite planned to be launched by the end of 12th Five year plan. India's Geosynchronous Satellite Launch Vehicle (GSLV-F08) successfully launched GSAT-6A Satellite into Geosynchronous Transfer Orbit (GTO) March 29, 2018. The updates continued till April 1, when ISRO announced the successful second orbit raising operation, carried out on March 31. The next orbit raising was to happen shortly afterwards, which would insert the satellite into the orbit it was destined for. But, after the flurry of updates, an ominous silence followed. ISRO finally confirmed it lost communication with the satellite on April 1. The satellite was on the last leg of its journey when the communication snapped. Indian space agency ISRO will launch GSAT-32 satellite in October 2019 to replace GSAT-6A which stopped communicating a few days after its launch on March 29.

South Asia Satellite was a communication satellite built by ISRO to provide a variety of communication services over the South Asian region. ndia made a promise to extend the advanced space technology for the cause of growth and prosperity of the people of South Asia and felt that the successful launch of South Asia Satellite marks a fulfillment of that. For this, it was equipped with Ku-band transponders. GSAT-9 satellite was configured with 12 Ku-band transponders and to be positioned at 48ºE. The satellite was configured with 2000 Kg class (I-2K) bus with a power handling capability of around 2.8 KW and a lift-off mass of 2350 kg. GSAT-9 carried 12 Ku band transponders with India coverage beam and a GAGAN payload. The platform system was based on I-2K satellite with a liftoff mass of 2330 kg and payload power of 2300W. The satellite was planned to be launched during 2013-14 by GSLV. India's Geosynchronous Satellite Launch Vehicle (GSLV-F09) successfully launched the 2230 kg South |Asia Satellite (GSAT-9) into its planned Geosynchronous Transfer Orbit (GTO) May 05, 2017.

GSAT-14 satellite with 6 Extended C band and 6 Ku band transponders was envisaged to enhance communication transponder capacity. The satellite employs the standard 2000 Kg class bus (I–2K) with a power handling capability of around 2.5 KW and a lift-off mass of 1980 kg. GSAT-14 was intended to serve as a replacement for EDUSAT as the spacecraft was configured with 6 Ku and 6 Ext C band transponders providing India coverage beams. In addition, the spacecraft also carries Ka band beacons, which are planned to be used to carry out studies related to rain and atmospheric effects on Ka band satellite communication links in Indian region. The spacecraft weighs around 2050 kg. The Geosynchronous Satellite Launch Vehicle (GSLV-D5) with an indigenous cryogenic engine & stage injected the GSAT-14 Communications Satellite, weighing 1982 kg, into a precise Geosynchronous Transfer Orbit on 5th January 2014 from Satish Dhawan Space Centre, Sriharikota.

In September 2018 the Indian Space Research Organization (ISRO) chose Arianespace to launch its GSAT-31 and GSAT-30 telecommunications satellites. The two satellites are to be launched on separate Ariane 5s from the Guiana Space Center, Europe’s Spaceport in Kourou, French Guiana from end 2018 onwards, starting with GSAT-31. Both satellites will be designed, assembled and integrated by ISRO. They are planned as replacement satellites for the currently operational satellites providing key national services in multiple frequency bands including C- and Ku Bands. GSAT-31 will be based on an enhanced I-2K platform, to be stationed in geostationary orbit at a longitude of 48° East. It will weigh 2,500 to 2,600 kg. at launch. Providing communications to India, it will replace Insat 4CR, whose end of life is soon expected.

GSAT-8, India’s advanced communication satellite, was a high power communication satellite being inducted in the INSAT system. Weighing about 3100 Kg at lift-off, GSAT-8 was configured to carry 24 high power transponders in Ku-band and a two-channel GPS Aided Geo Augmented Navigation (GAGAN) payload operating in L1 and L5 bands. The 24 Ku band transponders will augment the capacity in the INSAT system. The GAGAN payload provides the Satellite Based Augmentation System (SBAS), through which the accuracy of the positioning information obtained from the GPS Satellite was improved by a network of ground based receivers and made available to the users in the country through the geostationary satellites.

GSAT-10, India’s advanced communication satellite, was a high power satellite being inducted into the INSAT system. Weighing 3400 kg at lift-off, GSAT-10 was configured to carry 30 communication transponders in normal C-band, lower extended C-band and Ku-band as well as a GPS Aided GEO Augmented Navigation (GAGAN) payload operating in L1 and L5 bands. GSAT-10 was the second satellite to carry GAGAN payload after GSAT-8, which was already providing navigation services from orbit. GSAT-10 also carries a Ku-band beacon to help in accurately pointing ground antennas towards the satellite. The 30 communication transponders onboard GSAT-10 will further augment the capacity in the INSAT system. The GAGAN payload provides the Satellite Based Augmentation System (SBAS), through which the accuracy of the positioning information obtained from the GPS satellites was improved by a network of ground based receivers and made available to the users in the country.

GSAT-15 was a communication satellite planned to be positioned at 93.5ºE with a lift-off mass of about 3100kg and 6.8 KW power generation capacity. It was expected to function with a mission life of more than 12 years. The satellite carried 18 Ku Band operational transponders and two channel GAGAN payload. GSAT-15 was planned to be launched onboard a procured launcher. The building of the GSAT-15 was part of the Indian Research Organisation’s (ISRO`s) efforts towards in-orbit spare capacity to meet contingency and to protect the services of existing users. The satellite provided required redundant capacity, will augment capacity in the Ku band, and shall provide in-orbit redundant requirement of safety of life operations benefitting civil aviation services in the country. Nine operational INSAT/GSAT satellites are currently providing different frequency bands to nearly 195 transponders. The GSAT-15 satellite covered the entire Indian mainland. All heritage proven bus systems will be used to build the satellite in 18 months. The satellite was similar to the GSAT-8. On 28 June 2013 the Union Cabinet gave its approval to the proposal for the GSAT-15 communication satellite project along with procurement of launch services and insurance. The building of the GSAT-15 was part of the Indian Research Organisation’s (ISRO's) efforts towards in-orbit spare capacity to meet contingency and to protect the services of existing users. The satellite will provide required redundant capacity, will augment capacity in the Ku band, and shall provide in-orbit redundant requirement of safety of life operations benefitting civil aviation services in the country. GSAT-15, India’s latest communications satellite, was launched successfully by the European Ariane 5 VA-227 launch Vehicle in the early morning hours of November 11, 2015. The 3164 kg GSAT-15 carries communication transponders in Ku-band as well as a GPS Aided GEO Augmented Navigation (GAGAN) payload operating in L1 and L5 bands.

GSAT-16 was a communication satellite planned to be positioned at 55ºE with a lift-off mass of about 3100 kg and 6.8 KW power generation capacity. GSAT-16 carried 24 C-band, 12 Ku-band and 12 Upper Extended C-band transponders. GSAT-16 satellite will support satellite based telecommunication, television, VSAT and other services in the country. It was expected to function with a mission life of more than 12 years. The satellite will carry 12 Ku, 24 C and 12 Extended C-band transponders. GSAT-16 was planned to be launched onboard a procured launcher. The Union Cabinet on 28 June 2013 gave its approval to the proposal for the GSAT-16 communication satellite project along with procurement of launch services and insurance. The project will meet contingency requirements, protect services of existing users and will augment and support existing telecommunication, television, VSAT and other satellite based services in the country. All heritage proven bus systems will be used to build the satellite in 24 months. The satellite shall be similar to the GSAT-10. The total cost involved in the project was Rs.865.50 crore including launch services. GSAT-16, was successfully launched at 0210 hrs IST December 7, 2014 by the Ariane-5 launch vehicle VA221 of Arianespace from Kourou, French Guiana. Ariane-5 precisely placed GSAT-16 into the intended Geosynchronous Transfer Orbit (GTO), after a flight of 32 minutes and 20.4 Seconds duration.

GSAT-17 was a communication satellite with a lift-off mass of about 3100 kg. GSAT-17 was planned to be launched onboard a procured launcher. After its lift-off at 0245 hrs (2:45 am) IST 29 June 2017 GSAT-17 became India’s third communication satellite to successfully reach orbit in the past two months. GSAT-17 was launched in the early morning hours using the European Ariane 5 Launch Vehicle from Kourou, French Guiana. The 3477 kg GSAT-17 carries communication payloads in C-band, Extended C-band and S-band for providing various services to the country. The satellite also carries equipment for meteorological data relay and satellite based search and rescue services.

GSAT-18 was a communication satellite with a lift-off mass of about 3100 kg. GSAT-18 was planned to be launched onboard a procured launcher. India’s communication satellite GSAT-18 was successfully launched on 06 October 2016 by a heavy duty rocket of Arianespace from the Kourou base of the French Guiana. GSAT-18 was the 20th satellite from ISRO to be launched by the European space agency and the mission was the 280th for Arianespace launcher family. ISRO, which has been dependent on Ariane-5 rocket for carrying its heavier satellites, was developing GSLV Mk III for this purpose. GSAT-18, built by ISRO provides telecom services for the country by strengthening ISRO’s current fleet of telecommunication satellites was launched into a Geosynchronous Transfer Orbit (GTO) about 32 minutes after the lift-off. Weighing 3,404 kg at lift-off, GSAT-18 carries 48 communication transponders to provide services in Normal C-band, Upper Extended C-band and Ku-bands of the frequency spectrum.

The first developmental flight (GSLV MkIII-D1) of India's heavy lift launch vehicle GSLV Mk-III was successfully conducted June 05, 2017 evening from Satish Dhawan Space Centre SHAR, Sriharikota with the launch of GSAT-19 satellite. This was the first orbital mission of GSLV MkIII which was mainly intended to evaluate the vehicle performance including that of its fully indigenous cryogenic upper stage during the flight. Weighing 3136 kg at lift-off, GSAT-19 was the heaviest satellite launched from the Indian soil. GSAT 19 is a communication satellite weighing about 3500Kgs to be launched onboard the first developmental flight of GSLV Mk III vehicle. GSAT 19 will carry 3Ka band, 2 C band and 2 MSS transponders.

The GSAT-29, which will link Jammu and Kashmir and the northeastern states under the Digital India programme, was put into orbit by India's latest and heaviest rocket geosynchronous satellite launch vehicle (GSLV-Mk III/D2) on 14 November 2018. The GSAT-29, with a life span of 10 years, is a multi-beam satellite that carries Ka/Ku-band high throughput communication transponders. It was intended to meet the communication requirements of users, especially in remote areas. In addition, several new technologies such as Q/V-band payload, data transmission through optical communication link would also be demonstrated helping realise future advanced satellites. The Q/V-band payload, data transmission through optical communication link would be used for satellite to satellite communication.

GSAT 20 is being configured as a Ka-band communication satellite.Isro is building high-throughput satellites like Gsat-11, Gsat-29 and Gsat-20 with high beam (a special kind of transponder that operates on a high frequency) that will increase our communication capabilities. Gsat-19 launched in 2017 used 16 beams and was able to transfer data at the rate of 13 Gbps. Gsat-20 will use 40 beams. Each beam will have two polarisations, which will effectively make them 80 beams. Gsat-20 will thus have data transfer rate of 60-70 Gbps. GSAT follow on Satellites including Launch Services: GSAT follow on missionsare the future communication satellites planned during the 12th Plan period. GSAT follow on missions Launch Services is envisaged for securing procured launch services for future communication satellites. A combination of high throughput satellites -- GSAT-19, GSAT-29, GSAT-11 and GSAT-20 -- would provide the high speed internet needed for the success of the Digital India program.

In September 2018 the Indian Space Research Organization (ISRO) chose Arianespace to launch its GSAT-31 and GSAT-30 telecommunications satellites. The two satellites are to be launched on separate Ariane 5s from the Guiana Space Center, Europe’s Spaceport in Kourou, French Guiana from end 2018 onwards, starting with GSAT-31. Both satellites will be designed, assembled and integrated by ISRO. They are planned as replacement satellites for the currently operational satellites providing key national services in multiple frequency bands including C- and Ku Bands. As for GSAT-30, it will be based on an I-3K platform, will weigh 3,450 kg. at launch and ensure continuity of service for INSAT 4A, positioned at 83° East longitude. It will provide high-quality television, telecommunications and broadcasting services.

Indian space agency ISRO will launch GSAT-32 satellite in October 2019 to replace GSAT-6A which stopped communicating a few days after its launch on 29 March 2018.

The three communication satellites GSAT-22, 23 & 24 will be configured with ISRO’s standard I-3K bus. These satellites will carry Ku-band transponders. The satellite subsystems were under various stages of realisation by early 2018.

GSAT-11 was an advanced communication satellite employing a 4000 Kg–6000 Kg class bus and was proposed to carry 32 Ku band user beams with corresponding gateway links operating in Ka band. The satellite will have power handling capability of around 10 KW. Spacecraft level Preliminary Design Review (PDR) has been completed and System level interfaces are finalized. The satellite is the third of the four satellites that will high-speed broadband connectivity to all parts of India, bridging the rural and urban divide. Two satellites, the GSAT 19 and 29, have already been launched and the fourth GSAT 20 was to be launched in 2019. GSAT-11 was based on I-4K bus which was under advanced stage of development. The spacecraft can generate 10-12 KW of power and can support payload power of 8KW. The payload configuration was on-going. It consists of 16 spot beams covering entire country including Andaman & Nicobar islands. The communication link to the user-end terminals operate in Ku-band while the communication link to the hubs operate in Ka-band. The payload was configured to be operated as a high data throughput satellite, to be realised in orbit in 2013 time frame. Indian Space Research Organisation’s (ISRO) heaviest and most-advanced high throughput communication satellite GSAT-11 was successfully launched from the Spaceport in French Guiana during the early hours 05 December 2018. The launch vehicle Ariane 5 VA-246 lifted off from Kourou Launch Base, French Guiana at 02:07 am (IST) carrying India’s GSAT-11 and South Korea’s GEO-KOMPSAT-2A satellites, as scheduled. Even with ISROs advanced ‘Bahubali’ rocket, the GSLV Mk III, India is not capable of launching this heavy satellite. GSLV Mk III can support a liftoff mass of 4 tonnes, which is double the capacity of its predecessor.