Experiencing Blocked A2P SMS Messages on T-Mobile? This Could Be Why

Written by Aaron Alter

If your SaaS company offers SMS messaging for anything from marketing campaigns to 2-factor authentication to appointment reminders, it’s possible you’ve run into issues with your T-Mobile traffic. We say this because we’ve had countless conversations with businesses looking for solutions to dropped or blocked messages on T-Mobile specifically. But why T-Mobile? 

T-Mobile’s Daily Cap

Each Mobile Network Operator (MNO) has a different cap on how many business (or A2P) messages can be sent within a given period of time. In other words, the MNOs have different message throughput limits. Verizon monitors throughput by messages sent per second at a per number level, and AT&T by messages sent per minute at a Campaign level. T-Mobile, on the other hand, monitors by messages sent per day at a Brand level. See below for a guide on T-Mobile throughput limits for A2P 10-digit long code (10DLC or local numbers) messaging from The Campaign Registry.

So… Why is This a Problem?

If your messaging API provider has the technology in place (which they likely don’t) to automatically lookup both your approved sending limits at the Brand and Campaign level as well as who each end user’s MNO is and how many messages each MNO is receiving at a time, T-Mobile’s daily limit isn’t a problem at all. At Telgorithm, we call this smart queueing – it’s the only way to proactively track and manage the needed information to support maximum send rates at the exact approved throughput limits across all your Brands and Campaigns, without dropping messages or risking blockages. 

The kicker is that Telgorithm is the only vendor offering this tech and process. 

The majority of vendors manage message throughput with something called “capping”, which means they send messages to MNOs at the lowest approved speed or limit across all your Campaigns (read more about capping here). Although capping causes unwanted sending delays and low messaging ROI, it can be used to prevent blockages for Verizon and AT&T recipients because of their per second and per minute throughput caps. 

Because daily limit capping is a lot more complex, providers have been simply lifting the ceiling and sending messages all at once for T-Mobile. Like we mentioned before, T-Mobile’s daily cap is set at the Brand level, which means that all Campaigns under a Brand collectively share the same daily limit – depending on how many total Campaign recipients are T-Mobile users and what your approved throughput limits are for each Campaign per Brand, lifting the ceiling could result in messages being dropped or blocked altogether. 

Even if your Brands (or customers) aren’t reaching T-Mobile’s daily limit today, you unfortunately won’t know until messages have already dropped, causing disruptions to your customers. This is why our proactive approach in smart queueing is the ideal path for guaranteed deliverability and peace of mind. 

Error Codes to Look Out For

To verify this for yourself, you can actually look at your current provider’s website and search “exceeding T-Mobile daily limits” or error codes. Twilio shows a 30023 error code for 10DLC messages, Bandwidth a 4780 error code (and a 4781 for AT&T) for 10DLC messages, and so on. 

Why would a provider create error codes for exceeding limits when they're responsible for managing them? (Plus, you’re still getting charged for dropped messages, including pass-through fees…)

Whether you’ve been experiencing dropped or blocked messages on T-Mobile or want to be proactive about preventing it from happening, please don’t hesitate to reach out for a consultation with one of our SMS experts. We’re always happy to help!