A2P 10DLC - Stay Compliant

      A2P 10DLC - Stay Compliant

        Article Summary

        Approved for A2P 10DLC, What's next?

        Once your A2P 10DLC application has been approved, carriers will continue to monitor your SMS traffic. If you fail to follow guidelines, especially in those first messages, carriers will randomly filter other messages across your account (not necessarily the first lead that had the violation) until you fully comply.

        Repeat offenders may have to their SMS cababilities in Close suspended.


        To avoid SMS filtering and repercussions to your SMS capabilities in Close, strictly follow the guidelines below:

        1. Consent and opt-in
        Ensure that you only send messages to mobile users who have provided consent (opted-in) to receive messages from you. If at any point SMS capabilities are suspended in your account, Twilio will require you to provide proof of consent for some random numbers.
        If you are getting consent through phone calls, then have the lead send the first message using a keyword like "START." This message will act as proof of consent.

        2 . Sender identification
        ​Every message you send must clearly identify you (the party that obtained the opt-in from the recipient) as the sender, except in follow-up messages of an ongoing conversation. That is, the first message should have an introduction of who you are and why you are contacting the end user.

        "Hey Brian, this is Carol from Close.com....."

        3. Opt-out language
        ​The initial message that you send to an individual needs to include the following language: "Reply STOP to unsubscribe," or the equivalent using another standard opt-out keyword, such as STOPALL, UNSUBSCRIBE, CANCEL, END, and QUIT.
        If you are contacting the same recipients multiple times per month, you do not need to provide opt-out instructions in every message, but you must do it at least once per month.
        If you are sending messages to users repeatedly over a long period of time, you should check in with your recipients at least once every 18 months to ensure they still want to receive messages from you. The mobile number you are sending messages to may have changed owners, or the recipient may not remember giving consent to receive messages from you.

        "Hey Brian, this is Carol from Close.com reminding you of our call at 3pm. If you no longer wish to receive SMS notifications, reply STOP"

        ​4. High-key messaging metrics

        Carriers will continuously monitor for two metrics:

        a)​​ Opt-out rate

        High opt-out rates indicate that you must be sending unsolicited messages to people who didn't explicitly opt in to receive messages from you. Such people are more likely to object and generate complaints, which will lead to your account being flagged for noncompliancy. Countinously monitor your opt out rate and review your lead generation methods if the rates are too high.

        ​b) High delivery error rate

        This covers errors:

        • 30003 - Unreachable destination handset
        • 30005 - Unknown destination handset
        • 30006 - Landline or unreachable carrier
        Lots of failed deliveries indicate:

        ​a) You may be attempting to contact numbers that are no longer in service, or are unreachable, such as landlines and/or external carrier filters, are refusing to deliver your messages.
        ​b) Same or similar message sent across a large number of phone numbers - We do not permit bulk sending identical messages across many phone numbers in a short time framne without prior business justification.

        c) Number of incoming messsgaes

        When the ratio of incoming to outgoing SMS on a Long Number is more than 1:3 (Outgoing SMS -> Incoming SMS), it signals to carriers that your recepients aren't engaged thus they may not have opted into your messages.

        5. Message contents

        a) URL shortening: Do not send links that have been shortened using shared public URL shorteners, such as TinyUrl or free Bitly links. United States carrier policies discourage the use of shared public URL shorteners, and state that your URL shortener should be both proprietary and properly branded (details here).

        b)Don’t use emojis, lots of exclamation marks or unnecessary special characters/capitalization, and watch your grammar and spelling. Typically, these messages are structured in a way to attempt to evade detection of unwanted messaging, and your messages will be filtered.

        c) Do not send content that is illegal in your sending area, or is forbidden by carriers. See Forbidden message categories for SMS and MMS in the US and Canada for additional information.

        6. SMS Character Limit

        A single SMS message technically supports up to 160 characters, or up to 70 if the message contains one or more Unicode characters (such as emoji or Chinese characters).

        However, modern phones and mobile networks support message concatenation, which enables longer messages to be sent. Messages longer than 160 characters are automatically split into parts (called "segments") and then re-assembled when they are received. Message concatenation allows you to send long SMS messages, but this increases your per-message cost, because SMS are billed per segment. See more here. When your messages per second increases, you are likely to appear like you are bulk messaging which will lead to filtering.


        Ensure your messages, especially templates used in workflows, stay below the 160 character limits.

        Why do message filtering systems exist?

        Message filtering systems exist for two reasons:

        1. Protecting mobile subscribers from unwanted messaging such as spam, fraud, or abuse

        Unwanted messaging is a huge issue in the messaging industry; unwanted messages can result in complaints, fines, or outright disconnection by carriers. Mobile users who receive lots of spam or other unwanted messages may decide to start opting out of or ignoring all messages from businesses, even legitimate ones who follow all rules and best practices.

        For these reasons, it is in everyone’s interest – Twilio(our telephony partner), wireless carriers, regulators, and most importantly our customers – to ensure that unwanted messaging is not allowed over Twilio’s carrier connections.

        2. Enforcing rules or regulations about what types of messaging are allowed to that country or mobile network

        Depending on the country, laws or regulations may put restrictions on certain types of messaging, or even forbid certain things altogether. Messages which violate these rules may be subject to filtering.

        These rules and regulations may also change over time. In the U.S. and Canada, application-to-person (A2P) type messaging was historically not allowed to be sent using local 10-digit long code phone numbers. In 2021, however, Twilio and U.S. carriers are launching the A2P 10DLC(coming soon to Close as well) solution which permits A2P messaging via long code to United States recipients.

        How do spam filters work?

        Spam filters vary heavily from carrier to carrier, and can be changed overnight without warning. If you are hosting a number in Close, SMS is taken care of by our provider, Twilio. SMS can be marked as spam by Twilio's carriers or the receiving leg’s carrier. Algorithms and systems will be scanning SMS for certain keywords, SMS length and other criteria that may come across as ‘spammy’ in nature and block them before they are delivered. Message filtering can range from a simple static list of prohibited terms, to advanced machine learning systems that constantly adapt based on the messages passing through them

        One SMS that you sent to a customer may deliver as expected today and the exact same message to another customer may be flagged as spam tomorrow. Close has no control over these filters and they are incredibly volatile. So keep reading for some more insight!

        How do I know if my messages are being filtered?

        You will notice an error on the SMS activity in Close. If you hover your cursor over the error message, you will see the reason why it was undelivered.Filtred messages will fail with Error 30007 "Message Delivery - Carrier Violation": The destination carrier is filtering out your messages for delivery. The content of your message was flagged as going against carrier guidelines.

        CleanShot 2023-01-11 at 15.43.20@2x.png

        If you are avoiding all of the above and notice your number is still being flagged as spam, reach out to support@close.com for next steps. Close does not control spam filters but we can loop in our telephony provider to give a more concrete reason why the SMS was blocked and point you in the right direction.

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