If You Are Not Receiving SMS Using External Delivery in iMonnit
Push Notifications in the PWA app as a free alternative to SMS
Monnit released Push Notifications in March 2025 which are a no-cost solution to paid Direct SMS. If you wish to pursue notifications on your mobile device at no cost, this is a great solution. You can set up push notifications after installing the PWA mobile app with the steps in this article: Enable Push Notifications in iMonnit.
External Delivery
The iMonnit External Delivery SMS system that sends SMS at no cost is designed to send SMS notifications via email-to-SMS gateways provided by wireless carriers. This is a service whereby carriers convert emails into text messages for their subscribers. While this has been a long-standing method, many carriers, including major providers like Verizon, T-Mobile, and AT&T (and others), are increasingly phasing out or limiting support for these gateways, especially for commercial or automated messaging.
This change in carrier policy directly impacts the reliability of External Delivery (the free SMS service). When a carrier no longer supports this gateway for messages originating from services like ours, they often refuse delivery of the SMS notification (which originate from alert@imonnit.com). This can manifest as delayed or undelivered messages.
Carriers filter messages from automated systems like ours, sometimes flag them as spam, or simply discontinue support for the email-to-SMS gateway for this type of use. Because the carriers control the delivery of these messages through their gateways, this service may be unreliable for Users with these such carriers.
Carriers ending Support
AT&T has announced they are ending support for this service in June 2025.
Verizon has announced they do not support this service for commercial purposes. Verizon customers can pursue this as a paid business feature.
Alternative SMS option
Fortunately, Monnit offers a paid solution (12 cents per message in the U.S.) that provides reliable SMS messaging which is not filtered by the carriers. You can avoid this issue by purchasing Notification Credits and using the paid Direct Delivery feature, which will deliver reliable direct SMS messages without using the carrier’s email-to-SMS gateway. To configure a User for Direct SMS:
No other changes are needed - after making this change, your User will receive Direct SMS messages that are not routed through the carrier's email-to-SMS gateway.
What You Might See If External Delivery SMS Messages are Blocked by the Carrier
If you find a Rule triggered in iMonnit but don’t receive an SMS, investigate the Rule escalation. This will help you determine if the SMS was sent:
If the SMS alert was triggered and sent from iMonnit, you can look at the Status column of the Rule History. If you see “SMS Sent via SMTP” (most common), “Soft Bounce,” or “Hard Bounce,” you may be experiencing this issue. In some circumstances, the messages may be delivered hours or days later. You may also experience this issue intermittently.
Intermittence
Our best estimation is that carriers rely on SPAM lists and message volume to determine whether to deliver using the email-to-SMS gateway. This means they may independently mark Monnit's IP addresses or domain (@imonnit.com) as undeliverable origins. As a result, the delivery of the free External Delivery can be intermittent.