Cost optimisation of A2P SMS delivery – The basics

Despite not offering an A2P SMS termination service, TMT ID is nevertheless closely connected to the SMS industry. Every month we help route billions of SMS messages for our customers using the fastest and most accurate technology and data available.

Over many years working in telecommunications technology I have found that companies who perform best are companies that calculate where and how to optimise the least cost for SMS termination. For me, this is not just a decision for the commercial teams within businesses, but a technical one too. Too many times I’ve witnessed engineers simply asking their procurement teams for an HLR lookup for their SMS delivery, without actually thinking about whether or not they need an HLR service or looking at each market or destination they send SMS to.

Let’s suppose you’re running an SMS business and you have traffic to multiple countries — in each country, you have different connections and/or suppliers that can terminate the messages locally for you. You will find yourself in a few possible situations.

1. A destination country for your text messages doesn’t have number portability (there are still many countries where MNP is not implemented) and your connections/suppliers charge you for delivered SMS.

In this case, all you need to do to ensure the correct routing of SMS is to have a good numbering plan lookup before sending the message down your routes. You will need to know if the number is valid, if it’s been allocated by the regulator to a telco provider, and which number type it is. If it’s a valid mobile number allocated to a Mobile Network Operator, you can send the SMS message to that number.

This is the least expensive type of query you can do, and the situation described doesn’t justify doing an HLR lookup. However, numbering plans and regulator allocations can be dynamic and can be affected by mergers and acquisitions between operators, which may make them even harder to maintain.

To help our SMS business customers, we created a product called TeleShield, which in its standard form checks if a number is assigned by the regulator to which operator, if it has the correct length, and which number type it is — for example, you may not want to send SMS to landlines.

2. A destination country for your text messages has number portability and your connections/suppliers charge you for delivered SMS.

For this case, I’ve seen many engineers asking for an HLR lookup, which in this case is not needed. For a simple SMS delivery, you do not need to pay more for the subscriber status information.

The least expensive way to optimally route those SMS messages is to do a number portability lookup. Typically, you need to look up the number in the portability database and if it’s not ported, you need to look up the numbering plan of the country. In some countries, you need to query a third party for the information — for example, access to the number portability database is by query only — or even ask the operators directly via different types of interconnects.

To help our SMS business customers, we created a product called Velocity — because it’s very fast and handles billions of numbers globally. In Velocity, we have what we call on-net destinations and off-net destinations. For on-net destinations, where we have a synced copy of the database, we look up the database and the numbering plan in less than 2.5 milliseconds from the edge of our global network nodes. For off-net countries where we have to query the database provider or MNOs, there is about 1ms of additional delay to this — but still extremely fast.

3. A destination for your text messages where you get charged by your downstream routes for sending all messages.

Regardless of whether that country has number portability or not, you may find that users change their phone number quite often and you get charged a lot of money for valid numbers that are no longer active.

This is the real use case for an HLR lookup, where the goal is to determine if there’s a subscriber connected to that number or not. This can only be done by interrogating the network itself. This is the most expensive type of query, and the one that takes the longest to resolve.

To help our SMS business customers, we created a product called Live. The query response of our Live service will return the current network and a subscriber status indication — that is, whether the number is present in its network.

To summarise, even if many in the industry refer to any lookup as an HLR lookup, you may not need them for all your destinations. You can use any of the query types below, depending on the specifics of the terminating country:

• Numbering plan lookup — covered by TeleShield
• MNP or NP lookup (which also includes numbering plan information) — covered by Velocity
• HLR lookup or subscriber status lookup (which also includes MNP and numbering plan information) — covered by Live