Mobile Satellite Services on the roll

stein@opensky

It has been a while since I looked into Mobile Satellite Services (MSS) – and also since I last commented on it here in my article from March 2020 on “Will satellite comms happen this time?”. As already indicated at that time, and even more today, at this stage there seem to be real traction and various high-profile initiatives in the area.

As a terrestrial mobile services guy, I am not fluent on all MSS terminology – so this article could partly be seen as some form of tutorial for myself and the likes of myself (maybe of use to others as well?). Although I am not a great expert in the area, I will try to give a high-level overview of what I see at the moment – but for a more comprehensive overview of mobile satellite services (Non-Terrestrial Networks -  NTN), see this paper from GSMA (i.e. as seen from the global trade association for mobile operators).

As can be seen from my earlier article, I may have a certain historical bias, but in my opinion, there are a few pre-requisites for mobile satellite services to take off and make a true global impact, including:

1. Avoidance of proprietary and expensive mobile devices

2. Integration with terrestrial mobile networks

3. Cooperation between mobile and satellite network operators

4. Functioning commercial agreements between them

5. Standards based global solutions

An important factor for the global success of terrestrial mobile services (i.e. GSM, UMTS, LTE, 5G – or 2G, 3G, 4G, 5G) is the availability of mobile handsets with affordable prices that can work across the world - in other words, handsets based on global scale through global standards developed by 3GPP. In contrast, devices for mobile satellite services have historically been proprietary and expensive and specialized for dedicated satellite networks.

Mobile devices with global scale and affordable prices already exist in the market. These have been developed and produced for every G since 2G by an ecosystem of mobile device vendors – and are operating with terrestrial 2G - 5G mobile networks. A pre-requisite for the availability of mobile handsets at affordable prices is therefore that mobile satellite services can work with standard terrestrial mobile devices.

Mobile devices for 2G – 5G are designed to work on 2G – 5G terrestrial mobile networks – and unless mobile devices for satellites are designed to work “Over The Top” of terrestrial mobile networks, integration with terrestrial mobile networks is required – and, if so, cooperation between satellite operators and mobile operators is required – also requiring commercial agreements between them.

Mobile networks and handsets for terrestrial mobile services from 2G – 5G are all based on standards developed by 3GPP – and with a commercial and interoperability framework maintained by the GSMA. For satellite integration with terrestrial mobile services to work and to scale, a 3GPP- and GSMA-based framework is needed also for MSS.

What looks promising at this stage for NTN integration with terrestrial mobile networks is that all the above pre-requisites seem to be happening. As referred to in my article from 2020, a cooperation agreement between the EMEA Satellite Operators Association (ESOA) and the Next Generation Mobile Network (NGMN) Alliance was announced back then – and the GSMA and the GSOA (Global Satellite Operator’s Association) is also in place now. Further, the 3GPP has been working on NTN-integration already from Rel 17. Recently, the GSMA and the European Space Agency (ESA) also renewed their Memorandum of Intent (MoI) to cooperate on innovation and terrestrial – satellite integration for 6G.

Some basics

Satellite constellations: Satellite networks can generally be divided into Geostationary Earth Orbit (GEO), Medium Earth Orbit (MEO) and Low Earth Orbit (LEO) satellite networks – meaning that the satellites circle the earth with a given distance of 36000 km, 2000-36000 km or <2000 km, respectively. A GEO satellite circles the earth at the exact distance of 35786 km matching the earth’s rotation so that it seems to be stationary as seen from the earth – while the MEO or LEO satellites circle so that they seem to be moving as seen from the earth – which requires a high number of satellites to always provide wide-area (or even global) coverage, i.e. service availability at any given location. The most relevant constellation to consider in this article, however, is LEO satellites.

Satellite network architecture: A traditional satellite network for Fixed Satellite Services (FSS) communicates via a stationary Earth Station (ES) on the ground via the satellite to a stationary (fixed) device on earth – and typical applications are broadcasting and various communication. FSS typically uses GEO satellites and Ka-, Ku- or C-band frequencies (ref. below), which provide quite high bandwidths. FSS devices are quite expensive and need directional (e.g. parabolic) antennas. Further, coverage cells on the ground are many orders of magnitudes greater than those of terrestrial mobile networks, which is a clear limiting factor for system capacity.

Mobile Satellite Services (MSS) operate in a similar way, except that the MSS devices are mobile and do not have directional antennas. Otherwise, traditional MSS also uses an Earth Station (which can also be mobile, e.g. on ships), but operates with dedicated MSS-identified spectrum, i.e. the “L-band” or the “S-band” (see below). MSS may use all types of satellite constellations, but the most relevant for this article is LEO.

Spectrum: The ITU has identified global or regional spectrum for MSS and for terrestrial mobile services (“IMT” = International Mobile Telecommunications in ITU terms) – for which the detailed available spectrum may vary between regions and countries. Spectrum identified for MSS include parts of the “L-band” (1-2 GHz) and the “S-band” (2-4 GHz). FSS typically uses the “C-band” (4-8 GHz), the “Ku-band” (12-18 GHz) and “Ka-band”” (27-40 GHz).

For 3GPP-based terrestrial mobile services (IMT) a range of spectrum bands have been allocated, in Europe e.g. 800 MHz, 900 MHz, 1800 MHz, 2100 MHz, 2300 MHz, 2600 MHz and 3600 MHz. It is also foreseen to use spectrum in the mmWave band (e.g. 26 GHz) for terrestrial mobile services – which currently is starting to get allocated in some countries. Although these spectrum bands are in the same range as for MSS services, the exact frequencies are different. There is, however, a fight among the various camps for new spectrum to be identified for their specific uses at every World Radio Conference. I will not get into more on this, but the next WRC is in October 2027 – and preparations / lobbying for this are already ongoing.

Latency: Due to the long distance from the earth, satellite communication will result in latency in signals. GEO satellites will introduce the highest latency while LEO satellites will introduce the shortest latency. For a GEO satellite the round-trip delay will be 240 ms (which provides limitations e.g. for voice communication) - while for a LEO satellite at 2000 km distance it will be 13.3 ms (which is acceptable).

Doppler: For MEO and LEO satellite constellations, there will also be a Doppler effect, since the satellites seem to be moving as seen from the earth (typically around 7 km/s) – which may jeopardize communication. This effect will depend on the altitude and number of satellites in the constellations.

Propagation loss: Due to the long distance from the earth, satellite communication will introduce propagation loss between transmitter and receiver. The greater distance between transmitter and receiver, the higher the propagation loss – and only a small fraction of the transmit power will arrive at the receiver. In most cases this requires Line-Of-Sight (LOS) – and buildings and trees may result in drop in communication. This may be, in principle, compensated by directional / high-gain antennas but for standard mobile devices this is not feasible due to power consumption and design constraints. Communication from indoors will thus be difficult.

MSS concepts

D2D and D2C: There are two concepts for MSS to work with terrestrial mobile devices that need to be elaborated on for those unfamiliar with terminology on mobile satellite services, one is Direct-to-Device (D2D) and the other is Direct-to-Cellular (D2C).

Direct-to-Device (D2D) bypasses traditional terrestrial mobile networks providing coverage in remote or underserved areas – and typically uses dedicated MSS spectrum (but can also use existing terrestrial mobile IMT spectrum - if access to this spectrum is available – which may require an agreement with the spectrum holder, e.g. a mobile operator). Key players like Apple and SpaceX, along with major mobile operators, are actively developing and deploying these technologies, leveraging both existing mobile spectrum and specialized satellite bands to create a more resilient and comprehensive global communication network. As an example, Apple’s iPhones are equipped with chipsets that can access the Globalstar satellite network for emergency messaging. In this D2D scenario there is no need for new and upgraded satellites – and in satellite terms, it is referred to as a “transparent payload”.

Over 100 telecom operators have partnered with satellite providers to develop D2D services. As of Q2 2025, 11 operators worldwide had a D2D service, including T-Mobile US and Telstra in Australia (both partnering with Starlink). All of these are currently limited to text message services, but many operators and satellite partners plan to launch voice services and data capabilities. There will be regulatory (co-existence) matters to resolve when using IMT spectrum, e.g. on how terrestrial frequencies can be used safely from space without interfering with existing terrestrial services, including across borders.

Direct-to-Cellular (D2C) satellite services enable standard mobile phones to connect directly to LEO satellites and use advanced satellites equipped with specialized technology and algorithms to act as virtual base stations in space. D2C uses standard terrestrial mobile spectrum and the satellite acts as a roaming partner within the terrestrial mobile network. D2C does not require users to purchase special equipment or install new apps on their phones. Companies like Starlink and AST SpaceMobile are leading in this technology, which works with existing LTE phones and will provide services such as texting, location sharing, voice and data. In the D2C scenario, satellites will need mobile base station functionality, which is not (yet) generally available - and in satellite terms, it is referred to as a “regenerative payload”.

Support for MSS in standards (3GPP)

3GPP has been working on MSS for some years – and the first support for MSS came with Rel 17 in June 2022, with products generally available today for 5G with “NR over Non terrestrial Networks and IoT over NTN. Rel 18 was completed in June 2024 – and both Rel 17 and 18 have support for D2D / transparent payload. In Rel 17, 3GPP defined two 5G radio access technologies for NTN:

• NR-NTN - part of the 5G NR radio interface family

• IoT-NTN - an extension of the 4G NB-IoT and eMTC radio interface family

In Rel 19, 3GPP will also include support for D2C / regenerative payload – and is planned to be frozen by 3GPP in late 2025. Products (in this case upgraded satellites) could therefore be available in 2026 - 2027.

MSS use cases and opportunities

According to GSMA Mobile Economy Report 2024, “there were 8.6 billion (terrestrial) mobile subscriptions by the end of 2023, surpassing the world’s population of 8.1 billion people. The number of unique mobile subscribers was 5.6 billion of which 4.6 billion were mobile internet users, representing 58% of the world’s population. “Furthermore, analysis of the global population distribution from GSMA concludes that mobile coverage is “concentrated within just 20% of the Earth’s landmass, even if mobile networks coverage extend beyond that still ample areas are not covered by terrestrial networks.”

As the debate about satellites versus mobile some decades ago is less pronounced today (MSS services have imitations in capacity, latency, indoor coverage etc), the general opinion these days is that there is obviously great scope for covering rural areas not covered by terrestrial mobile networks (as a complement). This may clearly be for devices with Line-Of-Sight, be it for consumers with a handset or for mobile IoT devices (e.g. in cars). Another relevant case would be Fixed Wireless Access (FWA) through satellite for households or businesses.

On top of that the majority of the globe is covered by oceans – which may need MSS coverage as well. It could be argued that mobile consumer devices at sea (or in aircraft) most likely will be covered by satellite through a fixed MSS device on the vessel, but on deck in a ship there might be a D2D or D2C opportunity as well.

Finally, as backhaul to remote rural areas is very difficult and expensive to build, satellite backhaul to remote base stations seems like a very good use case.

Beyond consumer communication, a lot of business or societal use cases may be relevant, e.g. emergency services (voice or messaging), vehicle-to-everything (V2X) communication, advanced telematics services, infotainment services to passengers wherever they are, sensors / smart meters, industrial IoT etc.

Market situation for mobile satellite services today

Terrestrial mobile services are typically operated by Mobile Network Operators (MNOs), or mobile operators in short, which have acquired allocated terrestrial mobile (IMT) spectrum. MNOs have licenses in and operate on a national basis in all the countries in the world through mobile base stations built on the ground across the country – and global services are provided through roaming between them. MNOs offer services to consumers and businesses through subscriptions.

Mobile Satellite Services (MSS) are typically operated by Mobile Satellite Operators (MSOs) which have acquired regionally or globally allocated MSS spectrum. MSOs own a number of satellites that have been sent into space, and which circle the earth in GEO, MEO or LEO orbits at various distances from the earth. MSOs provide regional or global coverage and services directly. When operating from space, the satellites cannot easily be upgraded and will generally stay until end of life. Historically, MSOs have used proprietary mobile devices for their specific satellite services and different from (terrestrial) mobile devices.

Basically, MNOs and also MSOs provide subscriptions directly to consumers and businesses. Having used different devices this has never been an issue – except for the historical battle around which service is best (ref. my earlier article here) – as the services have been quite distinct. When now the two services will operate on the same device (which obviously makes sense for the end customers), there could be a conflict between MNOs and MSOs around who interact with and own the end customer. It is therefore essential that there are good commercial agreements between them.

Without getting into specifics around MNOs, for which there are several hundred in the world, an overview of some of the important MSS players these days is given below. Some of these have existed for many years and some are newer. Some have also been more in the news than others. These days there seems to be another wave of MSS hype again, with announcements coming regularly not only from various MSS operators but also from industry associations – and there is progress in Standard Development Organizations (SDOs) like 3GPP. Maybe it is more realistic this time?

Using satellite (MSS) spectrum:

• Globalstar has 48 satellites in LEO orbit and uses the MSS L-band. A key player behind the company from the start was Qualcomm. Globalstar has gone through bankruptcy but is today back in business. Apple has recently invested in the company - and a new generation of satellites is under development. Services today are designed to cover 80% of the earth and are generally low-speed voice and data, emergency services and messaging. Globalstar operates without any MNO partners.

• Iridium (ref. also the earlier article) has 66 satellites in LEO orbit and uses the MSS S-band. Services are mostly IoT, messaging and low-speed voice and data. Iridium has also been through bankruptcy and is also back in business. Iridium was recently also declared compliant with 3GPP Rel 17 IoT-NTN. Iridium is partnering with multiple MNO partners for NTN.

• Skylo is a new and recent virtual satellite operator operating at GEO orbit in partnership with various existing MSOs (e.g. Viasat, Echostar, Inmarsat etc) and uses the MSS L- and S-bands. Services are IoT, messaging and emergency services – and is compliant with 3GPP Rel 17 IoT-NTN. Skylo is partnering with multiple MNO partners for NTN fallback.

Using mobile (IMT) spectrum:

• Starlink has thousands of satellites in LEO orbit (now just below 8000 satellites in orbit – planning to have 12000) and is designed to operate in MNO spectrum – thus it typically needs to partner with MNOs across the globe. Starlink is developed by SpaceX (owned by Elon Musk) and their main partner is T-Mobile in the US – where they operate in the 1900 MHz band. Starlink’s solution is what GSMA refers to as “LTE proprietary”. Their aim is to provide internet access, including mobile broadband, in underserved and remote areas across the globe. As of mid-2025 Starlink has been licensed to operate in 42 countries world-wide. Starlink recently (Sep 2025) also stated it will “acquire wireless spectrum licenses from EchoStar for about $17 billion, a major deal crucial to expanding Starlink's nascent 5G connectivity business. With exclusive spectrum, SpaceX will develop next-generation Starlink D2C satellites, which will have a step change in performance and enable us to enhance coverage for customers wherever they are in the world.”

By the way, Starlink’s is not the only player planning acquisition of Echostar spectrum in the US. Also AT&T and Verizon are in for the spectrum.

All the above MSOs are based on the (currently existing) D2D concept – except the future ambitions of Starlink for D2C.

MSS business models

In a D2C scenario, mobile devices will be standard terrestrial mobile devices (LTE, 5G etc) using IMT spectrum and MSOs will need to have roaming agreements with all MNOs for MNO subscribers to fall back to MSS coverage e.g. in rural areas. Likewise, MSO subscribers might also use terrestrial mobile networks when this is suitable (e.g. if the terrestrial mobile service is cheaper). This could well be the case, but it will depend on the exact MSO pricing models and roaming agreements.

In a D2D scenario with legacy MSS satellites using the MSS spectrum, which is what we generally see today, relevant MSS devices will need to be upgraded in compliance with 3GPP standards – and terrestrial fallback to satellites could happen with these devices (and vice versa). Commercial agreements between the MSO and all the national MNOs will need to be in place also in this case.

In all cases the MSOs will need licenses to operate in every country. In a D2C scenario they could borrow IMT spectrum from the licensed MNOs. They could also acquire their own IMT spectrum (which is what Starlink is currently doing).

If mobile devices for satellites are designed to work “Over The Top” of terrestrial mobile networks, the MSS service and MSS licenses are independent of terrestrial MNOs.

To summarize, going forward, as an end customer, I could either use my existing standard smartphone in a D2C scenario with my existing terrestrial mobile subscription – or I could use an upgraded mobile phone from the same brand in a D2D scenario. In the latter case, I might need an additional MSO subscription to use the satellite service – unless some “roaming-like” agreement will exist between the MSO and my MNO. Personally, I would clearly like to avoid having two subscriptions – but others might want to (?). With eSIMs it might be quite feasible to have multiple subscriptions, but this requires the MSO service to use a 3GPP compatible SIM for identification and authentication – which it may or may not.

So what is the future with Mobile Satellite Services?

1. This time I think it will happen. All the pre-requisites are there and there is now so much money poured into it - and so many initiatives taking place. According to Berg Insights, there were 5.8 million satellite IoT connections at the end of 2024, with Iridium, Orbcomm, Viasat and Globalstar the market leaders.

2. Mobile Satellite Services are a very good complement (not competition) to terrestrial mobile services, in particular for covering rural areas directly or through FWA or backhaul.

3. Integrated devices: MSS using the same devices as for terrestrial mobile services is key and seems to be happening (whether through D2D or D2C). With support from 3GPP and GSMA this will enable global scale.

4. Acceptable business models between MNOs and MSOs need to be established, however, so that all players get a reasonable revenue share and Return on Investment (RoI). For most MSS initiatives (D2D or D2C), I hope this is what may happen.

All in all, if all pre-requisites are in place, with good cooperation between the camps, be it locally or at industry level, and acceptable business models for all are developed, then satellite integration with terrestrial mobile will happen. For the end customer this will ultimately provide an extended and much better coverage – and for the world, it could improve public safety and connect the unconnected.

Final comments

I generally don’t want to make these articles too long – so I apologize for the length of this one. However, as it is partly intended as a general update and personal tutorial for myself as well, this is what it ended up with.

If you want a high-level update on what is happening with mobile satellite services, maybe it is a fit? If you are looking for a more detailed and more technical perspective on MSS / NTN, please have a look at GSMA’s overview.