When you send out mass SMS, it can happen that not all of the messages get delivered. Understanding why some messages are not delivered is important so that you can react when necessary. We listed the 4 main reasons why it could be that your SMS are not delivered and explain how you can solve them.
1. Invalid phone numbers
This is the most recurrent reason for undelivered messages. Invalid phone number errors are mainly due to people making typos when filling in forms or willingly giving a wrong phone number.
You may think that using the wrong phone number format, such as local instead of the international format for example, may increase the number of invalid phone number errors. But this is not the case: most tools, at least RingRing’s platform, process all phone number formats automatically so that the sender does not need take that into account.
There are a few ways to reduce the amount of invalid phone number in your CRM. You can start by adding a validation on the phone number format in the subscription form. You can also send users a one-time password that they need to fill in to validate the form. This way, you are certain that the phone number exists and that your SMS will be delivered.
2. Carrier filters
Some cell phone carriers filter the messages sent to their networks. They mainly do so to avoid spam and phishing attempts. Messages can be blocked by filters for two reasons: you try to send bulk SMS where all messages contain identical content or the messages you send contain a specific keyword that is not allowed.
To avoid having your bulk SMS undelivered, CPaaS such as RingRing can have your content pre-approved by the carriers. That way, your SMS will be delivered to the final users. The filtering on keywords is harder to manage: there is no official list on which keywords are forbidden, but applying logic and common sense when writing the SMS should be enough to avoid this issue.
3. Configuration & technical errors
This is a frequent source of undelivered messages. A lot of different actors have to configure something correctly in order for your message to arrive: you, your telecom partner, the network operator and the recipient. If one of these makes a mistake or has a technical issue, your message will not be delivered.
If the problem is on the side of the end user, he most probably has turned off his phone. There is nothing you can do except waiting for him to turn it on again. If the network operator has a failure, you can be sure that they will try to fix it as soon as possible. You cannot do much either, but most of the time, your messages are queued and will be delivered when the issue is fixed. Now, if there is a configuration issue either on your side or your CPaaS’ side, it needs to be corrected.
When messages are undelivered, RingRing helps its customers to find out why as fast as possible so that the issue can be corrected. When there are technical or configuration issues, we will provide a solution to them and help you implement it if needed. A status page of our services will keep you informed of issues on the network on the operator’s side.
4. CPaaS filters
Just as carriers do, CPaaS, such as RingRing also apply filters. These filters can be implemented to avoid spam and phishing, but also to prevent mistakes in mailings. For example, if you try to send an SMS of 1.000 characters, the rending will be bad for your recipient and you will pay a lot of money to have it delivered. Therefore, RingRing blocks them.
To help you avoid this, SMS sending platforms have a character count that gives you the remaining amount of characters for your SMS to be sent out well. Sending messages that are too long usually happen in very specific cases only, such as using email to SMS functionalities.
This functionality allows you to send an email from your regular email box that will be received by the recipient’s phone as an SMS. There will be no character count for SMS format in your email, so it may happen that you forget that you are actually sending an SMS and that your text will be way too long. To avoid this, RingRing blocks messages that are too long.
The reason why your SMS are not delivered can be different in each scenario. Your telecom partner should be available to help you identify the issue and help you resolve it. Do you have any undelivered SMS issues that you don’t understand? Let us know at firstname.lastname@example.org and we will gladly help you!