SMS Deliverability 101: How To Always Hit the Inbox with Marketing SMS

Good old SMS are still working like clockwork in marketing, including pay-per-call. Perceived equally well by consumers of all age groups and across industries, text messages have incredible conversion power if they hit the inbox without being blocked by the gateway or carrier.

High SMS deliverability – as close to 100% as possible, but no less than 98% – is at the core of successful text campaigns. No matter how brilliant your message is, you must deliver it first and ensure it’s formatted correctly so the recipient can see it.

Source: GIPHY

 

Read on to learn everything you need to know about SMS delivery, SMS deliverability, and how to always hit the inbox with marketing SMS.

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What Happens When You Send a Marketing SMS

As simple as SMS messages are, their path to the inbox might involve passing several carriers and gateways, each with its own rules. If your text messages are delayed or not delivered, you might need to update your understanding of how texting works.

Let me refresh it for you.

Step 1 – SMS Composition

You can create an SMS on a mobile phone or web application or use a dedicated system like E-Delivery. The standard SMS length is limited to 160 characters for the GSM 7-bit encoding (the standard encoding for a text SMS) and 70 characters for the Unicode encoding (the encoding for an SMS that contains special characters, emojis, and non-Latin scripts).

Longer texts are split into two messages—the so-called concatenated SMS—and then reassembled on the user’s device. The process is safe if the mobile network and the recipient’s device support concatenated SMS (most networks and devices do) and no segments are lost in transition (rarely happens). However, each concatenated SMS is billed separately, so sending such messages may not always be financially reasonable.

Step 2 – Processing by the SMS Gateway

Once your marketing SMS is ready, you can send it from your mobile device, web-based SMS platform, or API provided by your SMS gateway or service provider.

1. First, your SMS gateway or service provider (the gateway is an intermediary in the SMS delivery process).
2. Next, the message is sent to your mobile operator’s SMS Center (SMSC), which stores it for some time if the recipient is unavailable. If the recipient uses a different carrier, the SMS is transferred through an inter-carrier network.
3. SMSC determines the recipient’s location and forwards the message to the best-fitting cell tower or base station
4. The cell tower or base station sends the message to the recipient’s device and also issues an alert of the new incoming message.

For an SMS to go through, the gateway must verify the sender’s ID, username, password, API key, and other credentials. This important check prevents fraud and ensures compliance with standards like 10DLC and TFN.

What Is SMS Delivery?

SMS delivery is the percentage of messages that reach the recipients’ mobile devices. If 95 out of 100 messages are delivered, the SMS delivery rate is 95%. Most marketers believe a delivery rate of around 98% is good enough.

Note: High SMS delivery rates indicate that most messages are delivered to the recipient’s mobile device, but it’s still unclear whether the message goes to the inbox, the spam folder, or is blocked from being shown to the user.

What Is SMS Deliverability?

SMS deliverability indicates the percentage of SMS that reach the recipients’ inboxes AND are accessible for reading. A high SMS deliverability rate – the same 98% or higher – means the recipients see your messages and will engage if they are good enough.

SMS delivery rate shows whether messages technically arrive, whereas SMS deliverability shows how many of these messages hit the inbox without being damaged during transfer.

Why Are My Messages Not Delivering?

Wrong or Invalid Number	Messages delivered to the wrong number are useless because there’s little chance you accidentally hit a potential customer. An SMS delivered to invalid (non-existing) numbers just goes void, never received by anyone. The wrong formatting, like missing the international dialing code, can also cause delivery failure, although some systems can successfully recognize SMS without country codes.
The Phone Is Turned Off	If the recipient is out of reach for a long time—for example, they’ve lost their phone, the airplane mode is on, or they are out of coverage—the message may be discarded. Most mobile operators store messages for around 72 hours.
The Number is Blocked by the Recipient	If the recipient blocks your phone number via built-in blocking or third-party applications, your SMS will not be delivered. Also, some carriers allow users to block phone numbers on the network level. In this case, your SMS won’t even reach the recipient’s mobile phone.
The Inbox Is Full	For older phones—especially phones that store SMS messages on the SIM card—if the SMS storage space is full, the phone cannot receive new messages. Such exotic cases like this may prevent you from reaching the perfect SMS delivery rate even if you’ve done everything right.
Poor Sender’s Reputation	If you have a track record of violating regulations or sending spam messages, you might be blacklisted by the carrier or blocked by the carrier’s spam filters. Other factors affecting your sender’s reputation include SMS quality, formatting, engagement, volume consistency, and opt-in compliance.
Contested Mobile Network	Mobile networks may get congested during holidays, sports events, and emergencies, not allowing messages to go through on time or blocking them altogether (rarely happens). Likewise, SMS delivery rates drop during network maintenance and critical failures.
Filtering	Almost all mobile carriers automatically block SMS messages that aren’t up to their standards, like messages with blacklisted keywords and suspicious links. The filters vary, but the rule of thumb is that all unwanted messages are blocked.
Routing Issues	Messages coming through several different carriers are harder to send, with an increased chance of compatibility issues. For example, different carriers may have different protocols.
Gray Routes	Gray routes are unofficial SMS pathways that exploit legislation loopholes to send SMS cheaply. Gray routes usually result in inconsistent delivery and a higher risk of blacklisting.
Roaming	Delivering messages to numbers outside the home network is harder because of compatibility, routing, and security complexities. The longer the message’s path, the bigger the delay, while some messages may not be delivered.
Local Regulations	For international campaigns, you must comply with local data privacy laws, anti-spam regulations, and carrier filtering. These are the TCPA in the United States and the GDPR in Europe. For some countries, SMS messages can only be delivered during specific hours (in India, promotional messages are only allowed to be sent from 9 a.m. to 9 p.m.).

How To Improve Your SMS Delivery and Deliverability Rates

A complete overhaul of your SMS deliverability and delivery rates means identifying and fixing all issues on your side (you can’t affect the carrier but only change it if it’s responsible for low delivery rates).

Submit the Necessary Information to the Carrier

To pass the verification with your carrier, you have to submit your business name, address, SMS use cases, user information, and other details so they know who you are and what type of messages you are going to send to whom. Make sure to elaborate on the use case – the more details you provide, the greater the chance you’ll be approved.

Understand Your Phone Numbers and Carrier Limits

The verification depends on whether you use short code, local, toll-free, international numbers, or all of them (if so, you will have to clear all sets of requirements).

Short Code Phone Numbers	Short code numbers – for example, “12345” – are used for automated marketing campaigns, notifications, contests, or messages sent by triggers. You can easily find a carrier with a throughput of around 100 SMS per second and 10,000 SMS per day. The sending limits vary depending on the niche, business scale, SMS quality, and other factors. Example: “Text DISCOUNT to receive a 35% discount on your next three purchases.”
Local Phone Numbers	Local numbers – for example, (415) 555-1234 – are used to connect local customers with customer support and send appointment reminders and local promotions. The sending limits are around 1 to 3 messages per second. Example: “Reply YES to confirm your tomorrow’s appointment.”
Toll-Free Phone Numbers	Toll-free numbers—for example, 1-800-555-1234—provide free customer support, tracking, and shipping services. The sending limits are 3 to 5 messages per second. Example: “Text HELP for immediate free assistance.”
International Phone Numbers	International phone numbers – for example, +44 20 7946 0958 – are used for global promotional campaigns and customer support. The sending limits vary depending on the carriers in question and the destination country’s regulations. Example: “For non-US residents, text HELP for support.”

Not all businesses are allowed to send SMS from all phone numbers. In highly regulated industries like finance or healthcare, you may have to comply with additional requirements and have stricter limits on the volume, time, and type of messages you can send.

Opt-In or Double Opt-In Your SMS Recipients

With more and more users having concerns about online privacy, it’s crucial to send SMS to people who have requested to receive your messages. Also, specifying your opt-in methods to the carrier will increase the chance of approval.

To increase the quality of subscribers, you can use double opt-in, requesting an additional confirmation after the initial consent. For example, after the user has requested to receive messages on your website, you can ask them to confirm their subscription via email.

Cleanse Your SMS Lists Regularly

While double opt-in is a great strategy for collecting a list of high-intent subscribers, it’s not enough to keep the list relevant. As your subscribers change their phone numbers or simply disengage, you have to remove them from the list of recipients to stay cost-effective.

The cleansing rules may vary—for example, you might want to try re-engaging inactive recipients a few times until you give up—but it’s still important that your subscriber list is up-to-date so you don’t waste your resources.

Avoid Blacklisted Words and Phrases

All carriers have a list of words and phrases associated with low-quality, overly promotional, and deceptive messages. “Urgent,” “respond now,” or “you are a winner” are quite risky and may lead to restrictions and penalties, even if the message is legitimate.

Source: GIPHY

 

The quality of your messages is the top concern for the carrier. Quality texts receive more engagement and improve your sender’s reputation, whereas dubious texts reduce SMS delivery rates and kill your sender’s reputation.

Start Slowly Before You Ramp Up the Volume

Warm up your campaign before you reach your target volume. Carriers monitor the behavior of new senders thoroughly, so it’s better to increase your sending volume consistently over a month or so – say, by 3% per day.

Send SMS When Users Expect Them

There are two basic strategies for sending marketing SMS messages:

Sending SMS by Triggers	Customers are most susceptible to marketing SMS messages right after they’ve completed a registration, added items to the cart, or made a purchase. Strike while the iron is hot. Omnichannel marketing software can make triggered SMS campaigns much more accurate, allowing you to reach users who engage with other marketing channels: email, social media, etc.
Sending SMS When Users Are Active	If you have access to engagement analytics – part of Phonexa’s software suite – you can send messages when your users are more prone to making purchases. If you don’t have any data to rely on, you can send your texts around 10 a.m. and 4 p.m., when most customers are active.

Consistency is also important for high SMS delivery rates, so stick to the same patterns with your messages. For example, if you provide bonuses after the first and the second purchase, customers will get accustomed to receiving treats, and it might be better not to disappoint them.

Understand and Differentiate Between SMS Delivery Error Codes

Error codes returned by your mobile carrier, SMS gateway, or SMSC are incredibly helpful for optimizing your SMS campaigns. However, although there are some common SMS error codes – for example, the 401 code means the sender is not authorized to perform the requested action – most codes differ between providers.

Track and Optimize Your SMS Campaigns

Alongside using error codes, you can use dedicated SMS marketing software to track and optimize your campaigns in real-time and strategically.

Phonexa’s E-Delivery is a perfect example of all-encompassing SMS software that enables granular campaign tracking and detailed reporting while also using data from other marketing campaigns like email, social media, and paid advertising. As a result, you can dig into the data much deeper than most marketers, customizing your messages for every recipient.

Here are some essential features you get with E-Delivery:

• In-depth segmentation: Behavioral, geographic, and demographic data from your SMS and other campaigns will allow you to refine your SMS list so you can send the right SMS to the right recipients at the right time.
• Comprehensive reporting: Campaign, delivery, recipient, and geolocation reports will ensure you have the most detailed information about your campaigns and can create tailored messages for your customers.
• A/B testing: With A/B tests, you can find which SMS campaigns perform better, optimizing up to six templates simultaneously.
• Custom tracking URL and shortener: You can add custom domains to track URLs in your messages and automatically shorten your domain links to improve the aesthetics of your messages.
• Automated campaign management: Automation management and failover automation optimize resource spend so you don’t waste time and money on repetitive tasks.

 

Ensure Compliance and Compatibility with All Your Carriers

Whether using a dedicated SMS platform like E-Delivery or sending marketing SMS on your own, compliance might be one of the biggest challenges, especially for global campaigns and campaigns involving multiple carriers.

For this reason, I recommend using certified products like Phonexa. This way, you can achieve compliance, mitigate risks, protect your customers, and have peace of mind when unrolling your campaigns.

Phonexa’s products have the following certifications:

• AICPA SOC 2 Compliance Certification
• iClear Fraud Prevention, Data Verification and Hygiene, Data Append
• ISO/IEC 27001:2005
• ISO/IEC 27001:2013
• CDSA Certificate of Compliance
• PCI DSS
• HIPAA
• CIPP US
• TRUSTe
• CCPA
• STIR/SHAKEN

Phonexa’s infrastructure provides high redundancy, ensuring your business stays online 24/7.

Ensure 99.99% SMS Deliverability with Phonexa – and More!

E-Delivery and Opt-Intel are a powerful combo that ensures all your SMS and emails get where you want them to. But you can achieve even more if you integrate E-Delivery and Opt-Intel with other Phonexa’s products for performance marketing.

All eight Phonexa’s products work in sync to help you get the most out of your email, social media, SMS, phone call, SEO, paid advertising, and affiliate campaigns. A complete marketing ecosystem, Phonexa covers your marketing from top to bottom so you can generate or buy leads in bulk with minimum effort (and at the best price) and confidently drive them to conversion.

 

Here are the eight proprietary solutions you get at a single price starting at $100 a month (online price calculator):

LMS Sync	Lead tracking & distribution software
Call Logic	Call tracking & distribution software
E-Delivery	Bulk email & SMS marketing software
Cloud PBX	Cloud phone system
Lynx	Click tracking software
Opt-Intel	Suppression list management software
HitMetrix	User behavior recording & analytics software
Books360	Automated accounting software

Get your all-in-one performance marketing automation software suite now, or request a demo to learn more about Phonexa.

Frequently Asked Questions

What does it mean when a message is delivered?

If the message shows as “delivered,” this means it has successfully reached the recipient’s mobile device without being blocked, changed, or damaged. Technically, this means the recipient’s mobile network has sent a confirmation to the sender’s network that the message has been delivered.

What is the difference between sent and delivered text messages?

Not all messages that are sent are automatically delivered to the recipient. Some may get blocked because of compliance issues, carrier issues, or issues on the sender’s side.

What is an SMS delivery report?

An SMS delivery report is a notification sent by the carrier to the sender, indicating whether the message was delivered, delayed, or failed. The report also includes information like message ID, status code, timestamp, and more, all of which you can use to ensure compliance and optimize your performance.

Why do some of my texts not go through?

If your text messages are not delivered, there may be issues with your or the recipient’s carrier, mobile network, or compliance. Likewise, you might be sending an SMS to the wrong or invalid phone number or include suspicious links or content.