William Dudley DeMystifying Messaging Series, MMS, Network, RCS, SMS

Demystifying the US Messaging Ecosystem: Part 1: A Comprehensive Macro View

This post marks the commencement of my Demystifying the US Messaging Ecosystem series, an in-depth multi-part exploration of the intricate world of mobile messaging, focusing on the United States. Over the course of this series, I will dissect the various layers and components that constitute this vital communication channel as well as postulate where it might all be headed. The overarching objective is to provide a thorough, accurate, balanced, and accessible understanding of the forces shaping the messaging landscape, ranging from the regulatory frameworks that govern its operation to the technological infrastructure that enables seamless interaction and the key entities that drive its evolution. It will also attempt to dispel misinformation that is very prevalent about key stakeholders in this complex ecosystem. By the end of this series, readers will gain a comprehensive grasp of the US messaging ecosystem and its profound impact on how businesses connect with their audiences.

Following this August 2025 post, I intend to publish 2 posts each in September, October, and November – each a deep dive into key aspects of this dynamic ecosystem.

The Duality of the Ecosystem: P2P and A2P Messaging

The US messaging landscape is a dynamic and multifaceted environment, characterized by a complex interplay of technologies, regulations, industry bodies, and market forces. To truly grasp this ecosystem, it is essential to first differentiate between the two primary types of messaging traffic: Person-to-Person (P2P, also Consumer) and Application-to-Person (A2P, also Business or Non-consumer) – or a Duality, for sure.  Each with its own stakeholders, connections, governance, and certainly billing / financial arrangements.

Consumer Messaging (also called P2P Messaging): This is the familiar, everyday communication that occurs between two individuals using applications on their mobile devices. We have always called it Person-to-Person or P2P.  Traditionally, this has been dominated by SMS, with MMS, as people would share richer media (images, videos, etc.) but, in the last 12 months, the ecosystem is undergoing a rapid transformation. A notable shift in the US market occurred between September 2024 and January 2025, where P2P SMS traffic volume dropped by 50% as consumers began upgrading to iOS 18. This upgrade enabled a seamless transition to Rich Communication Services (RCS) messaging between iOS and Android devices, effectively moving a massive volume of P2P traffic off the traditional SMS channel.

The P2P messaging category includes traffic from Over-the-Top (OTT) messaging service providers like TextNow, Pinger’s TextFree, and TextMe, along with many others, which offer free messaging and operate over data connections rather than traditional carrier SMS networks, yet interoperate with mobile carrier subscribers through SMS. There are millions to tens of millions of active subscribers on these services. Many are from disadvantaged socio-economic groups. In fact, for many an ad-supported free texting/calling service has become a lifeline.  At this point, I don’t believe any have actually completed the migration to support RCS yet.  But it is likely in the near future. They would certainly benefit, and these companies have the capabilities to comply with GSMA Universal Profile that the current RCS standards are based upon.

Non-Consumer or Business Messaging (also called A2P Messaging): This is any communication sent from a business application or platform to a consumer. A2P is the critical channel for business-to-consumer (B2C) engagement and is the primary focus of this series. Unlike P2P, the US ecosystem has evolved to support A2P messaging through multiple, distinct pathways, each with its own unique characteristics, use cases, and regulatory / governance requirements.  Based on the type of sender ID used, A2P Messaging is further categorized as Short Codes, Toll-Free Texting, and 10DLC.

Understanding how these different messaging types and channels coexist is fundamental to navigating the nuances of the ecosystem. The entire system is held together by a network of key players, from the messaging intermediaries that bridge the gap between businesses and carriers to the regulators who ensure a fair and safe environment for all participants.

And A2P Messaging also includes SMS and MMS messages – each still part of the sender ID category above. It also now includes RCS Business Messaging, or RBM. RBM only recently become fully functional across iOS across all major carriers, as it had already been functional across Android for some time. We will go into more details about the RCS / RBM ecosystem in a future post – but certainly, the duality is still very much in play for RCS.

All stakeholders in this ecosystem have “paid their dues” to be here – sometimes overcoming numerous competitive threats. New parties have entered the ecosystem over the last several years, and a few have become key national players. As this ecosystem evolves, some of the existing stakeholders will be pushed aside as newer ideas prevail. That is part of the dynamics of the US mobile messaging landscape. While some may call this ecosystem a monopoly, the overriding truth is that it is indeed always changing and evolving as all parties involved strive to keep MNO based messaging safe, effective, and useful for all consumers. Market forces, not some nefarious collisional entity will evolve this ecosystem quite quickly. 

The A2P Messaging Channels:

The A2P ecosystem in the US has matured to offer businesses a choice of three primary channels, each with distinct advantages and use cases.

10DLC (10-Digit Long Code): The newest and fastest-growing A2P channel is 10DLC, which allows businesses to use standard 10-digit phone numbers as a business’s sender ID for their A2P communication needs. This channel has seen explosive growth due to its low cost, local feel, and high deliverability. The foundation of this growth is the centralized registration system managed by The Campaign Registry (TCR). Based on my estimates,  there are approximately 2.8 – 2.9 million active 10DLC campaigns with around 4 million brands registered with TCR, as of this writing. Around a year ago, this was 2.2-2.3 million active campaigns from around 3 million brands.  This indicates a massive and dynamic ecosystem where businesses are either actively using or preparing to use this channel, which is why you still see more brands registered than actual campaigns. Most brands, only register a single messaging campaign.  But some may register many – a few, even dozens, as businesses seek to diversify their consumer messaging outreach. 

Diagram illustrating the US Mobile Messaging Ecosystem, showcasing the interaction between P2P (Person-to-Person) and A2P (Application-to-Person) messaging channels, along with key players, registries, and their interconnections.

Figure 1: This shows the duality of the US mobile messaging ecosystem with P2P coupled with 10DLC A2P. Key players and messaging flows are shown. Entities shown on the purple ovals are all interconnected. Registries used for the messaging are highlighted, but actual registration or numbering reference connections are not shown.

Short Codes: For many years, Short Codes (typically five or six-digit numbers) were the gold standard for high-volume A2P messaging, used for everything from marketing promotions and loyalty programs to two-factor authentication. In fact, until 10DLC and toll-free number originated texting became officially sanctioned by the US carriers, short codes were the only truly sanctioned A2P channel for a long time.

Today, short codes are known for their high throughput and deliverability. While there is no single public registry that reports the total number of active short codes, the scale is significant. A major A2P messaging intermediary like ClearSky, which acts as an aggregator for smaller carriers and OTT providers, reports access to over 15,000 short codes. Given the role of aggregators, this figure likely represents a significant portion of all active short codes in the marketplace.

Diagram illustrating the US mobile messaging ecosystem, depicting the relationships between P2P (Consumer-to-Consumer) and A2P (Business-to-Consumer) messaging channels. It highlights key players, registries, and the flow of messages among various entities.

Figure 2: This shows the duality of the US mobile messaging ecosystem with P2P coupled with short-code A2P.  Key players and messaging flows are shown.  Entities shown on the purple ovals are all interconnected. Registries used for the messaging are highlighted, but actual registration or numbering reference connections are not shown.

    Toll-Free Texting: Another long-standing A2P channel is Toll-Free Texting, which leverages existing toll-free numbers (e.g., 800, 888) to send and receive text messages. The primary advantage is the ability for businesses to use a single, well-known number for both voice calls and SMS/MMS. According to Somos’s TSS Registry, which manages these numbers, over 5 million toll-free numbers had been text-enabled as of a few years ago. I expect this has been relatively stable since that time. This channel is particularly well-suited for two-way conversations and customer support, where continuity, as well as brand identity is key.

    Diagram illustrating the US mobile messaging ecosystem, detailing the P2P (Person-to-Person) and A2P (Application-to-Person) messaging pathways. Key players and their interconnections are represented, along with active registries for messaging services.

    Figure 3: This shows the duality of the US mobile messaging ecosystem with P2P coupled with toll-free A2P messaging.  Key players and messaging flows are shown.  It should be noted that some of the CPaaS providers may have begun to break the Toll-Free Gateway monopoly, with direct connections for toll-free messaging traffic to the carrier.  Entities shown on the purple ovals are all interconnected. Registries used for the messaging are highlighted, but actual registration or numbering reference connections are not shown.

    The Key Players and Their Interrelationships

    The US messaging ecosystem is held together by a network of interconnected entities, each with a specific role.

    Major Mobile Network Operators (MNOs): The three dominant forces are the MNOs (or carriers, as we sometimes refer to them as) that own their own network infrastructure. They control the flow of traffic for hundreds of millions of subscribers and set the rules for what is allowed on their networks. Based on recent data from Q2 2025, their market share is highly consolidated:

    • Verizon: ~146.1 million subscribers (~36% market share)
    • T-Mobile US: ~132.8 million subscribers (~33% market share)
    • AT&T: ~118.2 million subscribers (~29% market share)

    It’s also worth noting the recent acquisition of UScellular’s wireless operations and customer base by T-Mobile on August 1, 2025. This further consolidates the market under the “big three” and eliminates a key Tier 2 player.

    Tier 2 Carriers and MVNOs: This space is increasingly important and dynamic. Beyond the major MNOs, key players include:

    • Dish Network: Operates Boost Mobile and is building its own 5G network.
    • Cable Companies: Companies like Charter (Spectrum Mobile) and Comcast (Xfinity Mobile) have become major players, leveraging their existing home internet customer bases to become significant mobile carriers. As of Q1 2025, Spectrum Mobile had over 10 million mobile lines, and Xfinity Mobile had over 7.8 million lines as of Q4 2024.
    • OTT Service Providers: Services like Google Fi, which uses a combination of multiple networks, and the free texting apps mentioned earlier, also hold a unique position in this landscape.

    Messaging Intermediaries and Aggregators: These companies, such as Sinch and Syniverse, act as a vital bridge between businesses and mobile carriers. Instead of building direct connections to every carrier, a business can connect to a single intermediary that provides access to a massive number of endpoints across multiple channels (10DLC, short code, toll-free). As we saw with the ClearSky example, this aggregation role is critical to the scale and efficiency of the ecosystem.

    The Role of Registries and Regulatory Bodies: The integrity of the ecosystem is maintained by a complex web of governance.

    • TCR (The Campaign Registry): The centralized database that registers all 10DLC brands and campaigns. It is the key to ensuring transparency and accountability in this growing channel. With over 4 million brands now registered,  and with over 2.8 million active messaging campaigns, they play an important role in assuring that registered, sanctioned business messaging remains safe. Certainly, with bad actors trying every way possible to exploit messaging for their nefarious purposes, TCR registration and compliance helps ensure that good KYC practices, along with good documentation of messaging purposes, as well as consent methods used, help keep everything in line. The use of this, while sometimes controversial at times, has actually resulted in preventing many bad actors from trying to be seen as “legitimate” senders. Additionally, mobile carriers and DCAs  utilize TCR’s brand and campaign registration information to audit and enforce compliance and keep  subscribers safe.
    • The Short Code Registry: The formal registry for all short codes, responsible for managing the provisioning and leasing of these numbers. In other words, this is where you go to search for and lease your short codes that will be recognized by all carriers and ecosystem stakeholders.  Short code campaigns (or messaging initiatives) do have similar KYC and vetting as 10DLC; however, this is done through cooperation with the carriers directly, typically through A2P messaging service providers. 
    • Somos’ TSS Registry: The authoritative registry for text-enabled toll-free numbers, ensuring proper routing and management of that traffic.
    • NetNumber: A crucial behind-the-scenes player. NetNumber provides foundational “number intelligence” data and services like its netnumber Services Registry (nnSR®), which ensures messages are routed to the correct provider. Their Dynamic DNO service is also essential for helping carriers and providers comply with recent FCC mandates to block fraudulent traffic from Do-Not-Originate numbers.
    • TCPA (Telephone Consumer Protection Act): The federal law that sets the legal framework for consent and messaging practices in the US.
    • CTIA (Cellular Telecommunications Industry Association): The trade association that provides and maintains the well-referenced CTIA Messaging Principles and Best Practices, which are widely adhered to by carriers and businesses to ensure a healthy messaging environment. This document even provides the definition of what constitutes consumer messaging (e.g. P2P messaging) vs. business messaging (e.g. A2P messaging), in clear, concise terms.
    A Glossary of Key Terms

    10DLC (10-Digit Long Code): A standard 10-digit phone number used for A2P messaging as the sender ID.
    A2P (Application-to-Person) Messaging: Messages sent from a business to a consumer.
    CTIA (Cellular Telecommunications Industry Association): A trade association that sets industry guidelines.
    MNO (Mobile Network Operator): A company that owns and operates its own wireless network. Also called carriers, especially in the US and Canadian markets.  We use the term interchangeably.
    MVNO (Mobile Virtual Network Operator): A company that sells mobile service by leasing network capacity from MNOs.
    P2P (Person-to-Person) Messaging: Messages sent between individual consumers.
    RCS (Rich Communication Services): The next generation of messaging that provides rich media, read receipts, and more interactive features, often replacing P2P SMS along with it’s Business to Consumer variation called RCS Business Messaging or RBM.
    Short Code: A five or six-digit number used for high-volume A2P messaging. Before the advent of 10DLC originated messaging and toll-free number originated messaging, this was the only fully sanctioned A2P channel in the US market for many years.
    Somos’s TSS Registry: The authoritative registry for text-enabled toll-free numbers.
    TCR (The Campaign Registry): The centralized body for registering 10DLC campaigns.
    TCPA (Telephone Consumer Protection Act): A federal law regulating telemarketing and text messaging.

    Looking Ahead

    This introductory post has provided a high-level overview of the key players, concepts, and regulations that shape the US messaging landscape. In the subsequent installments of this series, we will delve deeper into each of these areas. We will explore the technical aspects of each messaging channel, dissect the nuances of compliance, and examine the emerging trends that are poised to transform how businesses and consumers interact. By breaking down the complexities of this dynamic ecosystem, the aim is to empower businesses to navigate the messaging landscape effectively, build meaningful connections with their customers, and leverage the full potential of mobile communication in a responsible and compliant manner.

    Next time (1st half of September):  Understanding A2P and P2P Messaging.  In this post, we will explore the fundamental differences between A2P and P2P messaging. How is P2P specifically defined?  What is and is not classified as P2P (or consumer to consumer, as it is now called)? We’ll look under the covers of the A2P ecosystem for more details, certainly looking at The Campaign Registry for 10DLC messaging, as well as short code, and toll-free messaging and outline some of the standards and best practices from carriers’ Codes of Conduct to TCPA, and of course CTIA documents.