Using an SMS Aggregator > Advantages and Disadvantages
The biggest advantages to using an SMS aggregator are scale and reliability. Sending millions of messages directly to the carrier's infrastructure is exactly what these companies specialize in, and they've been doing it for years. If you're going to run a large scale operation, working with an aggregator is really your only long-term option (short of working directly and individually with the carriers, an option that won't be explored in this guide).
Another advantage is the rich feature set that the carriers make available. You have access to their APIs, including batch sending, via a wide variety of protocols, and you can even send premium SMS messages.
The biggest downside to using an SMS aggregator is cost. As described in the "Chapter 5" section, you end up paying for all the messages sent and received by your service. Success can be costly. It's also worth reading the Premium SMS section of this guide carefully, as much of what we discuss there applies to aggregators in general (e.g., the 3 to 4 month approval process).