An SMS aggregator is a wholesale intermediary that connects messaging platforms and businesses to many mobile carriers so that business text messages can reach phones on those networks. Instead of each texting provider negotiating with every carrier, the aggregator holds those connections and agreements and carries traffic between them. In most cases you don’t buy from an aggregator directly: your CPaaS, contact center or texting provider does, and the aggregator’s routes shape how reliably and cheaply your messages are delivered.
Not to be confused with a telecom aggregator, which resells internet and network circuits from many carriers under one contract.
At a glance
- An SMS aggregator sits between messaging platforms and mobile carriers, holding carrier connections and agreements.
- It carries application-to-person (A2P) traffic such as alerts, reminders and verification codes.
- Most businesses reach aggregators indirectly, through a CPaaS or messaging provider.
- Route quality varies: approved routes and grey routes differ in cost, delivery and risk.
- Coverage, pricing and delivery reporting vary by aggregator and by country.
What problem it solves
There are hundreds of mobile carriers worldwide, each with its own technical interfaces, commercial terms and rules for business messaging. A company that wanted to text customers in several countries, or even across all the carriers in one country, would face a long list of contracts and connections. Most messaging providers don’t want to build all of those either.
Aggregators solve this by connecting to many carriers once and reselling that reach to their customers. A messaging platform can connect to one or a few aggregators and reach most mobile users in its target markets. Aggregators also handle much of the operational work: carrier billing, route maintenance, delivery reporting and, in some markets, passing registration data for senders and campaigns to carriers.
How it works
Connections. An aggregator connects to carriers’ messaging centers, usually over SMPP or carrier-specific interfaces, and offers its customers (gateways, CPaaS platforms and large senders) an API or SMPP connection in return. Some aggregators hold direct connections to carriers; others buy part of their reach from other aggregators, which adds another hop.
Routing. For each message, the aggregator chooses a route to the recipient’s carrier. To do that it often needs to know the current carrier for the number, which can change when a number is ported, so aggregators use number portability data or lookups. Routes differ in price, speed and whether the receiving carrier has approved them.
Approved and grey routes. An approved route delivers business messages through a path the receiving carrier accepts and charges for. A grey route delivers them some other way, for example disguised as person-to-person traffic or passed through another country to get a lower rate. Grey routes may look cheaper but are more likely to be filtered or blocked and can make delivery inconsistent. Many carriers actively look for and block this traffic.
Registration and compliance. In some markets, aggregators play a defined role in carrier messaging programs. In the US, for example, business texting from local numbers (10DLC), toll-free numbers and short codes each has its own registration or approval process, and aggregators and providers pass registration and campaign data to carriers. The exact roles and requirements vary by country and change over time.
Reporting. Aggregators pass delivery receipts back from carriers to the platform, which passes them on to you. How detailed and reliable those receipts are depends on the carrier and country.
For buying guidance on messaging platforms, see our communications platform as a service solution page.
When it matters for buyers
- Messages aren’t arriving. Delivery problems sometimes trace back to the aggregator route behind your provider, not to your content or registration.
- Comparing quotes. A much lower per-message price can reflect a lower-quality or unapproved route. Ask what is behind the price.
- Sending internationally. Aggregators differ in which countries they reach directly and which they reach through partners.
- Sending one-time passcodes. Verification codes are time-sensitive and a frequent target of fraud, so route quality and redundancy matter. See SMS for the wider picture.
- Building on a CPaaS. Your CPaaS provider’s aggregator relationships are part of what you are buying, even if you never sign with an aggregator yourself.
Questions to ask vendors
- Do you connect directly to carriers in our main countries, or through aggregators? Which ones, where you can say?
- How many routes do you have to each major destination, and how do you fail over between them?
- How do you make sure our traffic stays on routes the receiving carriers have approved?
- What delivery reporting do we receive, and how do you investigate a delivery problem?
- How do you handle number portability when routing messages?
- Which fees are carrier or aggregator pass-through, and how much notice do we get when they change?
- If an aggregator relationship ends, how would our traffic and registrations be affected?
How it differs from an SMS gateway
An SMS gateway is the entry point your application talks to: it accepts messages through an API, formats them and reports status. An SMS aggregator is the wholesale layer behind many gateways, carrying traffic to the carriers. Some companies run both a gateway and an aggregation business; many CPaaS providers run the gateway and buy aggregation from others. When you choose a provider, the gateway is what your developers see, and the aggregator routes are a large part of what decides whether messages arrive.