SMS Deliverability

Texting Filtering Information and Best Practices

In progress

Texting Information

All the information below has been pulled from the sources documented at the bottom of these pages.

Short code/Toll-free > Long Codes

To start, carriers do not allow application-to-person (A2P) on long codes and are subjected to filtering. This is to protect people from being spammed. It makes things harder for us marketers, but just think of your grandma getting a long code number text, with her area code, and this spammer wanting money for some local (fake) charity.

Long codes:

Slower Form Of Communication: Long codes were created for person-to-person communications “ and can send only 1 message per second” (Twilio).
Person-Person: designed primarily for peer-to-peer texting.
Russian Roulette: “Mobile vendors that allow you to send broadcast text messages from a long code are literally playing Russian Roulette with your list. Similar to an email spam filter sometimes messages make it through and sometimes they don’t.”
Human Restrictions: Longcodes should send to as many a human person would/could send in 24 okay
hour period

Short codes:

Faster Form Of Communications: “Short codes can send SMS and MMS at 100 messages per second”
Compliant For Mass Messaging: Short codes were created for mass communication and do not get filtered or penalized for heavy traffic from the carriers.
Expensive: The downside to short codes is the price. They tend to have a hefty cost and take a bit of time to set up.

A2P Long Code (Verizon Only Now) and Toll-free:

Affordable: way less expensive than a short code or having to use a shared short code
Compliant And Fast Communication: They are provisioned by carriers to send hundreds of text messages within a minute.
Very new: downside is that it’s a new way of texting and it could get some restrictions added later on.

Other Information

What carriers are targetinging when they filter group messages/blasts.
- URLs (initial message)
- Pictures
- Message Length
- Spammy Attributes
- Certain Trigger Words (words unknown for SMS, but following Avoiding Spammy Content Tips in email as a guideline)

On some sending platforms we are able to see when a carrier blocks a message with a usual error code of: 30007 “Message Delivery - Carrier Violation.” Except, not all phone carriers let us know that the message was blocked like T-mobile and Sprint, they sometimes show it was delivered when in fact it wasn’t delivered.

The size of the list doesn’t matter when sending using a long code. Carriers will block any message they consider spammy no matter if your list consists of 8 or 20,000 contacts. Below is a little example:

Removing http: https: and sending links just with www.domain.com/purl so this allows it look like a person actually wrote the message.

Items to help messages look less like spam. If you think it looks spammy, it is spammy

Keep scripts as short as possible (think length of a tweet) for higher engagement. Each SMS to less than 160 characters (1 unit of SMS). If you exceed those characters, the SMS sending velocity jumps above the 1SMS/2 second threshold. Messages under 160 characters enjoy a 10x decrease in filtration rates versus messages over 160.
Avoid sending out the same/similar content to multiple numbers in a short space of time.
Try to avoid LOTS OF CAPITAL LETTERS, exclamation marks !!!!!!, and keywords that could trigger any alarm bells - “free”, “promotion”, “Limited Time”.
Keep your scripts personal and authentic! Simple scripts that read like a genuine text that you would send to someone you know is the key to getting a 2-way conversation started.
Scripts that end in a question get the most replies! So make sure to end your script with an authentic and engaging question. Try phrases like “can you make it?” or “are you all in?”
Limited use Emojis 😉for higher reply rates.
Respond with warmth even if the answer is no — it could become a yes next time. Try using “Understand that you’re busy. Maybe next time?”
For existing contacts, leave out the agent introduction since they’ve already been texted from that person before.
Mass identical body messages with massive numbers of identical messages tend to set off spam alarms. Try varying the message across students.

Adjustments To Make

Moving away from long codes to either short codes or toll-free
Making messages less spammy
Switching all urls to have no http: or https and just having www.domain.com/purl
Metering the sending so they flow out slower.
Bad phone number checks
Personalized auto responses
NEW Texting Platform

Steps to troubleshoot an SMS delivery problems

Check Twilio
Check different carriers (AT&T, Verizon, T-Mobile, Sprint)
Does it have links?
1. Remove links
2. Remove link connection method (i.e. http(s)://, but include www.)
3. Secure links
  1. Avoid shared link shorteners
  2. Check domain reputation of every redirect in the chain
  3. Make sure all links are secure
  4. Try to align all links under the same domain
4. Send links in separate message
5. Try different link domain
Change content (for more details: SMS-Messaging Guidelines)
1. Make shorter
2. Make more conversational
3. Increase personalization
4. Increase content variation between recipients
Request SMS responses
Change the delivery pacing
Change the delivery telephone number

Good Reads

Sources