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SMS Notification Troubleshooting

Troubleshoot issues with SMS notifications

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Pre-Checks

Please complete the Notification Troubleshooting Pre-Checks before proceeding with this article.

Depending on the country where you are located and which cellular provider you use, a variety of issues may affect your ability to receive PagerDuty SMS notifications. For these reasons, PagerDuty does not have full control over the deliverability of SMS notifications.

We highly recommend push notifications as your primary contact method, which happens automatically when you Log In to the Mobile App, and adding a notification rule for your mobile device. If push notifications are not a viable option, the following sections provide troubleshooting tips for SMS notification delivery issues.

Countries Eligible for SMS Notifications

You can review Supported Countries for the full list of countries that are able to receive SMS notifications from PagerDuty. Please check that your country is on this list before conducting further troubleshooting. Countries marked with an asterisk (*) indicate Partial Support due to local restrictions and regulations in the region.

In addition, we are not able to guarantee delivery of SMS notifications to numbers that are:

  • Landlines, including those with Text-to-Landline (TTL) services.
  • Voice Over Internet Protocol (VoIP) or virtual numbers.

Duplicate SMS Notifications

PagerDuty relies on third-party vendors to deliver SMS notifications. These vendors, in turn, rely on several SMS partners and carriers to deliver SMS to end users. PagerDuty relies on a delivery receipt from carriers and providers to determine if an SMS notification was delivered. If we do not receive a delivery receipt, PagerDuty takes a more cautious approach, and sends the notification again. If it turns out the first notification was actually successful, even though we did not receive a delivery receipt, this will result in a duplicate notification.

Regulatory Policies and Carrier Restrictions

SMS notification content and format are heavily regulated by governments and carriers due to concerns around fraud, abuse, and aging SMS infrastructure, which provides limited security and privacy. Vendors will drop SMS messages for regulatory non-compliance, as well as SMS messages that violate their message policies.

The list below does not represent an exhaustive list, or a deterministic set of filtering criteria, as carriers and governments do not publish or provide feedback on their policies.

  1. Messages containing URLs are highly likely to be filtered.
    1. Recommended Action: Do not include URLs in stakeholder updates or in any service logs that may make their way into the incident notifications.
  2. Messages containing sensitive words that mimic fraud, spam or marketing campaigns.
    1. Recommended Action: When possible, avoid words like "banking," "finance," "marketing," "sale," etc.

Messages Without Sensitive Content

If your SMS notifications do not contain sensitive content, but are still getting filtered, please try the following:

  • Submit a request to your mobile service provider, asking them to allow all SMS messages from PagerDuty numbers. You can download the most recent PagerDuty numbers from our vCard.
  • Use push notifications as your primary contact method.

For more information regarding the SMS regulatory landscape, and why PagerDuty recommends switching to modern channels, such as push notifications, please read 6 Best Practices for Seamless Notifications with International SMS.

Other Common Causes

Incorrect or Inactive Number

Navigate to your user profile's Contact Information, and double-check your phone number for errors or missing digits. Inactive and invalid numbers will result in delivery failure.

Blocked Number

There may be settings on your mobile device that block messages from unknown numbers, or you may have sent an opt-out reply (e.g., “STOP”) to block further SMS communications. Some carriers also restrict SMS messages from certain types of numbers.

Third-Party Apps

Issues may occur when delivering SMS notifications to virtual numbers from third-party messaging apps. In the event of an application outage or service degradation, users may not be able to receive the messages sent to their virtual number. We recommend sending SMS notifications to your primary mobile device instead.

Carrier Outage

Check with your mobile service provider, to confirm if there was an outage or service issue at the time you expected to receive the notification.

Roaming

Prior to traveling, check with your mobile service provider to confirm if there are any additional requirements or restrictions while traveling.

Mobile Device Settings

Check if there are any mobile device settings which may have prevented you from receiving the notification.

SMS Response Did Not Action the PagerDuty Incident

Dual-Tone Multi-Frequency (DTMF) Issues

Dual-tone Multi-Frequency (DTMF) signals, the beeping tones generated from keypad responses, allow you to navigate menus, select options, and input information. When the signal is interrupted or unclear, unintended behavior may occur.

  • Connection Issues: A weak signal, data packet loss, or overloaded infrastructure can disrupt the clear transmission of DTMF signals.
  • Carrier Issues: Compatibility issues, misconfigured system settings, or outdated equipment can sometimes cause DTMF signals to be misinterpreted. This can be more common with older phones or specific VoIP services.
  • Keypad Buttons: Worn-out or sticky buttons on your device's keypad may not register your presses accurately. Try cleaning them or using a different device.

Performing an Incident Action on an Old Notification

PagerDuty takes a cautious approach to notifications, so that older notifications do no overwrite newer, important incident state changes.

The following is a list of some incident state changes:

  • Escalations
  • The is incident is resolved
  • Reassigning an incident

Once an incident changes state, users can no longer take action on an incident using older notifications that were generated prior to the state change.

SMS Notification Responses

Due to a variety of factors, some countries may not support responding to SMS messages to acknowledge or resolve an incident, even if you can receive SMS notifications. Please see the full list in our Supported Countries article.

SMS Restrictions

Short Code Messaging Restrictions

Some mobile carriers restrict messages from, or to, short codes. If you aren't receiving SMS notifications from PagerDuty and your phone number meets any of the conditions below, you may need to contact your provider to verify that your account is allowed to receive SMS notifications from short codes:

  • Pay-as-you-go numbers.
  • Any number that was pay-as-you-go and is now on a standard plan.
  • Any number that is or was used by a business in the past.

Provider-Specific Issues with Short Codes

  • T-Mobile USA has a default content filter set. In order to remove the content filter set, you must specifically call T-Mobile and authorize PagerDuty's short code numbers: 73889, 42752, and 43105.
  • If you recently upgraded your device with T-Mobile, they may have put a block on the account that could prevent it from receiving short code messages.

Geographic Restrictions

SMS URL Content Restrictions

To comply with local laws and regulations, SMS messages will have URLs replaced with the words URL redacted in the following countries:

  • Malaysia
  • Philippines
  • Thailand

India's Do Not Disturb (DND) Registry

Users in India should make sure that their phone number is not in the national DND registry. India's government provides a lookup utility to determine if a number is listed there.

Message Length Restrictions

There is a maximum length of 1,600 characters for all SMS notifications that PagerDuty sends. Our incident notifications are designed to be under this limit.

If you use a custom Status Update Template and you notice messages are truncated, we suggest updating your templates to ensure the message length is under 1,600 characters.

Best Practices

We highly recommend using push notifications and Slack as your primary contact methods, as these methods are significantly more reliable than SMS.

Staggering your notification rules may also help SMS deliverability.

Updated about 2 months ago

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