Voice and messaging: a side-by-side comparison

50 years ago, Motorola engineer Martin Cooper made the first ever mobile phone call. He dialled a rival at Bell Labs and gloated about his invention. It was a huge breakthrough. Of course, mobile has changed a lot since then. A phone is now a pocket computer that also serves as a camera, map, diary, music player and more.

Yet, for all the progress and the add-on functionality, voice remains central to the mobile economy. And it’s still growing. According to ResearchandMarkets, the global voice carrier market is expected to grow from $23,139.03 million in 2021 to $32,754.36 million by 2028.

But voice is not the only ‘legacy’ telco market that continues to prosper decades after it was first created. There’s also text messaging, which is now 31 years old.

In the early late 1990s, SMS was the new thing. There were world records for SMS speed typing and the sore thumb even became a medical issue. It’s all in the past now. Thanks to messaging apps like WhatsApp, person-to-person SMS volumes have decreased significantly.

But it’s a different story for business-to-consumer SMS. This new channel emerged in the early 2000s. It was created by a cohort of enterprising startups that saw the huge reach and high user attention of SMS among consumers.

So-called ‘Application to Person’ (A2P) messaging continues to prosper today. Industry analyst Grand View Research says the A2P market is worth $69.05 billion in 2023, and that revenues could hit $96.73 billion by 2030. Meanwhile, Mobilesquared estimates that just under 8 million global businesses were using A2P messaging in 2021. This is an increase of 20 percent compared to pre-pandemic times – but it still represents fewer than three percent of total registered businesses!

In 2023, the B2B markets for voice and text services remain in good shape. Each supports a healthy ecosystem of stakeholders. What’s more, there appears to be plenty of innovation around new products and services.

Yet, there are important differences between the two sectors. In this article, we will explore them. Let’s dive in.

Voice and A2P messaging: Definitions


Voice (specifically VoIP) describes the market of voice services where the buyers and sellers are telecom operators, carriers, specialist service providers and enterprises. These stakeholders trade in bulk voice traffic (either for P2P or B2C calls), often across different networks and international borders. The transmission of calls initiated from smartphones, computers, browsers or other devices is supported over an internet connection.

A2P (Application-to-Person) Messaging

A2P is the industry term for business messaging. It describes automated messaging that is sent by applications (rather than people) to individuals. Enterprises use the channel for many familiar purposes – to send transactional notifications, marketing promotions, service alerts, one-time authentication passcodes and more. A2P messages can be one-way (where recipients receive messages but do not respond) or two-way (allowing for a reply to the dedicated number).

While enterprises consume messaging services, this blog is more focused on the ecosystem of partners that powers the channel: telecom operators, carriers, and specialist service providers.

Voice and A2P messaging: Technical protocols

Voice and messaging traffic doesn’t just happen by magic. There is a complex infrastructure underpinning the billions of calls and texts that are routed every day. Here’s a summary.

Voice – the SIP standard

Today, people can make voice calls across a variety of devices (not just phones). They can either make them via the analogue carrier network or the internet (voice over IP). In order to ensure that calls can connect across this complex landscape, there must be an agreed set of rules around data exchange.

This is where Session Initiation Protocol (SIP) comes in. It sets the rules for the signaling process between two endpoints in order to create, maintain and end the call. These audio calls are converted into digital data, transmitted and then converted back into telephone signals on the user side. The industry has developed codecs to compress this data. G.711 is the standard codec for transmitting uncompressed data. Meanwhile G.729 transmits compressed data to reduce bandwidth requirements.

A2P Messaging – SS7 & SMPP

As with voice, messaging technology has evolved. First there were physical SS7 interconnections with leased lines. Then came SS7-via-IP (SIGTRAN), which is still used as the protocol within and between operator networks.

However, the dominant protocol for exchanging SMS over the Internet (with or without encryption) is now SMPP (Short Message Peer-to-Peer). The most commonly used version is SMPP 3.4 which was introduced more than 20 years ago but still caters for all needs. 

The messaging industry uses SMPP for high throughput ‘always on’ integrations. Service providers can employ it to submit hundreds of messages per second and receive their delivery receipts at the same time.

A2P Messaging – HTTP based APIs

In recent years, the industry has created HTTP based interfaces such as RESTful APIs. These APIs make it possible for enterprises to connect to manage messaging services from inside their own business software. The wider term for this process of giving control and convenience back to enterprises via APIs is communications platform as a service (CPaaS).

Voice and A2P messaging: Traffic volume, latency and quality

How do voice and A2P text differ in the way they consume network resources?


Voice deals with huge traffic volumes. Billions of voice minutes traverse the network every hour. Thanks to flexible codec usage this traffic does not consume a lot of network resources or bandwidth. But on the flipside, it is very sensitive to delay. A dropped packet cannot be retransmitted – it represents a disrupted audio stream. Because of this, latency is extremely important. It should be less than 150 milliseconds, while packet loss should be less than one percent.

A2P Messaging

A2P messaging traffic volumes are usually lower than voice calls. But the content can be urgent (especially transactional messages and one-time passcodes).  Quick delivery is a necessity, but real-time is not. That said, the delay between send and receive should be less than 10 seconds. Packet loss and high latency can still cause issues like unstable binds or message re-submission but it’s far less sensitive than voice.

Voice and A2P messaging: Business model

How do the stakeholders in voice and A2P organise their contracts?


One fundamental difference between voice and SMS is that the voice industry usually charges by the duration of a connected call, while the SMS industry charges per submitted message.

The voice industry uses a cost-based business model where operators negotiate rates based on minute volumes, quality of service, and termination destinations. So-called locked (exclusive) deals are a common feature. Here, a service provider commits to carrying a set volume of voice traffic through a specific operator. In return, it might receive discounted rates, priority routing or other incentives. Profitability is based on cost management, efficient routing, and termination rates.

Over recent years rates have dropped significantly and margins are small. In some cases, operators charge more for voice calls originating from specific regions. This is known as Origin-Based Rating for Voice Surcharge Zones. This approach started with network operators of the European Economic Area (EEA) that agreed on regulations for implementing lower rates on calls initiated and terminated in the EU region and for those originating from the EU region and terminating in other countries outside it. The model divides the countries outside the EU into different groups. As a result, the surcharge rates vary, which brings challenges of maintaining them, CLI validation, correct invoicing and dispute avoidance.

A2P Messaging

A2P messaging prices are typically based less on cost and more on market rate. Service providers charge enterprises or other service providers for the transaction of a message, usually based on the addressed destination and the desired quality of service. Traffic is rarely locked which causes the industry to be more dynamic.

SMS pricing itself changed dramatically over the past few years. Some previously expensive countries –  Germany for example – are now cheap compared to more highly monetised networks. In expensive regions, solutions such as number lookup can help by reducing the volume of messages sent to out-of-use numbers.

Voice and A2P messaging: Innovation in voice and SMS

Let’s summarise some of the new services emerging in the two markets.


  • Voice Broadcasting allows businesses to send pre-recorded voice messages to a large number of recipients simultaneously. It can be used for notifications, reminders, marketing campaigns and emergency alerts.
  • Click2Call lets a user initiate a voice call by clicking a button on a website or in an application.
  • Interactive Voice Response (IVR) is useful for customer care. It offers customers automated menus and prompts for resolving their queries. They can navigate through options and respond either by voice or DTMF tones. The use of IVR menus is less common in SMS, although USSD, OTT channels and chatbots can offer this functionality in a messaging context.


  • Text-to-speech enables a business to convert a text message into a voice call. The recipient receives a call, and when answered, the SMS is read out.
  • Flash calls have emerged as an alternative to one-time SMS passcodes. They replace the SMS with a voice call that the recipient does not answer. Instead, the last digits of the call number comprise the 2FA code. Flash calls can be cheaper than text OTPs while it requires user awareness and also adjustments in applications.

50 years after voice was ‘invented’ and 30 years after texting ‘became a thing’ both sectors continue to support vast ecosystems of service providers – while delivering compelling benefits for enterprises.

If you would like to know more, please get in touch here.

Global Telco Consult (GTC) is a trusted independent business messaging consultancy with deep domain knowledge in application-to-person (A2P) services. GTC provides tailor-made messaging strategies to enterprises, messaging service providers, operators and voice carriers. We have expertise in multiple messaging channels such as RCS, Viber, WhatsApp, Telegram and SMS for the wholesale and retail industry.

GTC supports its customers from market strategy through service launch, running the operations and supporting sales and procurement. The company started in 2016 with a mission to guide operators and telcos to embrace new and exciting opportunities and make the most out of business messaging. For more information or industry insights, browse through our blog page or follow us on LinkedIn.

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