Now that OpenMarket has announced the availability of US long codes, let’s review the differences between US short codes and long codes for SMS messaging. The table below illustrates these differences.
| US Short Code | US Long Code | |
| Format | A 5-6 digit number (i.e. 10958) | A 10 digit number (i.e 1-646-553-5219) |
| Uses | Marketing, Emergency Alerts, etc. | Non-Marketing, Customer Service, and Operational |
| Throughput | High Throughput (10 TPS+) | 1 TPS |
| Delivery Receipts | Supports delivery receipts | Not supported |
| Setup Time | 6-8 weeks | 5-10 days |
| Costs | CSCA lease fees, Operator filing and change fees | No operator or industry fees |
| Regulatory | Operator approved programs, Risk of unintentional consumer opt-out of all short code messaging | Immediate code shutdown for marketing or spam messages |
| CTIA Guidelines | A2P Guidelines | P2P Guidelines |
In summary, US long codes have fewer costs, are faster to setup, and come with less regulatory overhead than US short codes. However, they are limited to 1 message per second, which means that if you want to communicate with multiple end users at the same time, you will need multiple long codes. US long codes don’t support delivery receipts, so you won’t know for sure if your message has been received unless the end user responds. US long code programs aren’t officially registered with the mobile operators, so if there is an issue, like an end user complaint that they didn’t want the message, the long code may be immediately terminated. With US short codes, since the programs are approved and registered, operators follow due process to investigate any issues instead of immediately terminating the code.
US long codes can only be used for non-marketing use cases. So, if you plan to send advertisements, coupons, information about sales, or other promotional messaging, you must use a US short code. Nonetheless, US long codes are an efficient and cost-effective option for many non-marketing use cases – including improving your operational efficiency and customer experience.
Improved Two-Factor Authentication (2FA)
One example of where US long codes can be used to complement a US short code is in a Two-Factor Authentication (2FA) program. We would recommend using a short code as your primary 2FA originator. The built-in high throughput of a short code lets you easily allow more than one user to login to your site per second without having to use different codes for different users. The availability of delivery receipts gives you more insight into how the 2FA program is working. You’ll know whether the 2FA messages have been delivered or not, which makes your 2FA analytics more accurate and improves your ability to troubleshoot issues. Additionally, because this is a mission critical flow, the added comfort of knowing the carriers have this program registered is worth it.
Now, you may experience a few challenges with using a short code. Some of the users of your site may have put a block on short code messaging. They may not realize this block is in place, or they may have purposefully done it because they’ve been spammed before. In either case, odds are they didn’t intend to prevent themselves from receiving the 2FA messages from your site. Other users may be on an MVNO which isn’t setup up to support SMS messaging or they might be roaming. When these users try to login to your 2FA protected site, the 2FA message won’t be able to reach their mobile phone.
Since your short code based messages won’t be able to reach the end user, you also won’t be able to send them a short code based message to inform them of the issues or how to resolve them. You could call the user and verbally explain the situation, but odds are they would feel that’s invasive and probably don’t want to talk to you. The user might call customer service with a complaint, which can be costly and can damage your brand image. A better option is to use a combination of a short code for the initial 2FA message and a long code message if the delivery fails for the short code. You could use the long code message to send instructions to the user about how to remove the short code block, to inform them that their MVNO doesn’t support short code SMS messages, or to deliver the one-time pin until the issue is resolved.
This is just one example of where a US long code can be used to improve an operational use case. Another example is a company messaging its employees. In that case, the company can use US long codes and not have to deal with opt-in guidelines the way a business would when sending marketing messages to their customers. Whether it is your 2FA program, your HR program, your customer support inquiry program, or your appointment scheduling program, OpenMarket can help you create the ideal mobile messaging strategy.