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Shared or Dedicated Short Code: Choosing the Right One

For many people worldwide, SMS-enabled devices have become irreplaceable tools to stay connected with the outside world. Immediately communicating with customers, clients, employees, and members therefore makes SMS an extremely powerful messaging tool for businesses. When considering a short code, the following preliminary questions will be a helpful in evaluating your mobile communication goals:

  • What is the mobile communications budget?
  • What is the timeline to launch a mobile communications campaign?
  • What are the text message volume needs?

There are two short code options for companies to engage their audiences with text messaging: shared short codes and dedicated short codes. Which one is the best choice for your business?

Shared Short Code: Lower Cost, Quick Launch, & Shared Volume

Shared short codes allow a business to run a campaign on a short code that is used by other companies. The primary benefit is a savings in both money and time. Shared short codes cost less than dedicated short codes because a single shared short code is used across various text messaging campaigns run by multiple companies. Dedicated short codes typically cost $500 per month to lease with a $3,000 carrier application processing fee, plus the cost to send each message. Tapping into a short code that is already active saves you the time of obtaining and provisioning a short code yourself (typically an 8-10 week process or more) – plus you can launch your text messaging campaign almost immediately.

Separate campaigns are able to run simultaneously on a single short code with the use of keywords. A keyword is a unique phrase assigned to a short code that identifies a business campaign. For example, Dr. O’s dentist and Sal’s Pizza both use short code 55616 to communicate with their customers. Dr. O uses the keywords SMILE and CLEAN for two separate campaigns: texting SMILE to 55616 subscribes the user to appointment reminders; and the CLEAN keyword designates a special offer Dr. O’s office is running this month. Sal’s Pizza uses CHEESE so subscribers can subscribe to delivery specials. The unique keywords allow businesses to share the use of a short code.

Dedicated Short Code: Brand-Friendly, Better User Experience & 35 Dedicated Messages/Second

Dedicated short codes are an excellent mobile tool for businesses requiring sole use of the short code. While it costs more money and time to launch a dedicated short code, there are certain advantages to consider: they are brand-friendly, offer a better user experience, and handle a higher throughput of text messages.

A short code can become part of a company’s brand strategy particularly with a vanity short code, which allows you to specifically request the numbers of the short code. This might be used to mimic a zip code, or an associated word (e.g., 76453 spells SMILE). Vanity short codes cost $1,000 per month to lease, whereas a random short code costs $500 per month and is randomly assigned.

The second advantage of a dedicated short code is better user experience. With a shared short code, the user will typically have to text a keyword, and then an action word to subscribe. For example, Dr. O wants to run two campaigns with the keyword SMILE. This first is for appointment reminders, as mentioned above, and the second is appointment confirmations. Since both use the keyword SMILE, each campaign should be designated with an action word. The user would text SMILE RMD to set up SMS appointment reminders. When they receive the reminder (e.g. “Your appointment is 3/30/10. Txt SMILE Y to confirm”), the user needs to text the keyword SMILE plus the action word Y for yes in order to route the response to the correct company. With a dedicated short code, this is not necessary.

A dedicated short code can send up to 35 text messages per second. On a shared short code, this volume is shared among the number of companies using a single short code.

CDYNE provides U.S. and Canadian short codes for use with the SMS Notify! API – SMS Notify! is a secure two-way SMS Gateway that facilitates your business communications with a developer-friendly API.

Get more short code information, or test today for free.

Previous blog: Text Messaging: Almost a Guaranteed Read
Next blog: Dedicated Short Code: Steps to Launch

Text Messaging: Almost a Guaranteed Read

Your cell phone beeps, buzzes, or blinks – signaling an incoming text message. How many seconds will pass before you respond and pick up the phone to check the message? How quickly will you respond? SMS is a highly effective and engaging medium of communication and multiple studies show that 95 – 98% of text messages are read within minutes of receipt. Due to the prevalent use of cell phones for text messaging (the Pew Research Center reports that 80% of U.S. cell phone owners use their phone to send and receive text messages), mobile communications provides a huge opportunity for businesses to connect with their audience and engage in immediate and relevant conversations. In the U.S. and Canada, the best way to do this is by using a short code.

A short code is a special 5-6 digit number (e.g., 75195) that allows consumers to subscribe to mobile messaging campaigns. You are probably familiar with ads prompting you to text a keyword to a short code, for example, “Text PIZZA31 to enter to win a free pizza.” Whether SMS communication with your audience is for informational, promotional, voting, feedback, or other contact, there are significant benefits in adding SMS communications to reach your audience:


Short code messages are typically delivered within seconds. This is an immediate advantage for businesses engaging their audiences in real time, and has a broader appeal than an app download or mobile website. 91% of all U.S. citizens have their mobile device within reach 24/7 (Morgan Stanley).

Near Perfect Open Rates

The average open rate for SMS messages is over 95% (Frost & Sullivan). This makes SMS a powerful marketing tool and gives businesses a direct line of communication to support other marketing efforts.

Targeted Communication

There are many opportunities to reach your audience with short codes that range from information and customer service (e.g., opt-in alerts and logging customer issues) to marketing, advertising, and entertainment (e.g., incentives, promotions, polling, games, and  quizzes). A big appeal for companies using short codes is reaching each subscriber in a personal, relevant and timely manner.

Customer Communication Choice

Customers have increased expectations of the companies with which they do business. For many consumers, text messaging is a preferred method of contact, and a golden opportunity for a company to increase the frequency of one-to-one communications.

CDYNE provides U.S. and Canadian short codes for use with the SMS Notify! API – SMS Notify! is a secure two-way SMS Gateway that facilitates your business communications with a developer-friendly API.

Get more short code information, or test today for free.

Next blog: Shared or Dedicated Short Code: Choosing the Right One

Send SMS to Over 200 Countries & 800 Carriers

SMS Notify! supports text messaging worldwide with the potential to reach over 5 billion people globally.  You can reach this network of mobile users by purchasing a UK DID for assignment to your SMS Notify! license key. When you pass a phone number with 011 + the country code, the API will automatically use the UK DIDs assigned to the license key for sending the text messages.

Unicode Support

Another great feature is Unicode support. Unicode is a standard for handling text in all writing systems, and allows you to send text messages in many languages. It provides a unique number for every character, and allows text data to pass through many systems regardless of the platform, computer program, or programming language used. You should note that that the receiving device determines which characters it will display. While it may support Unicode, it may not display all Unicode characters.

Unicode covers any language that can be written in a script (e.g. Latin, Greek, Cyrillic, Han, etc.), which is an inventory of graphical symbols.  For example, a single script such as Latin may be used to write hundreds of languages (e.g. English, Spanish, and West Germanic), whereas a single language like Japanese may use multiple scripts including Han, Hiragana, and Katakana.

Which Encoding Does SMS Notify! Support?

To send Unicode messages using SMS Notify!, set the IsUnicode parameter to True in the AdvancedSMSSend method. The API supports UTF-16, which is a character encoding for Unicode. Unicode text messages are 70 characters per transaction. Non-Unicode messages are 160 characters.
By default the IsUnicode parameter is set to False. In this instance, SMS Notify! supports Latin-9, or ISO/IEC 8859-15 encoding which are 160 characters per transaction.

A Couple of Tips for Sending International Text Messages

  • 011 + country code + phone number in the PhoneNumber parameter when sending messages outside of the U.S. and Canada. SMS Notify! will automatically send from your International DIDs.
  • Some international carriers use spam-filters which block messages based on content. Check out the Carrier Restrictions tab (Excel doc) for more details.


Contact CDYNE for more information about Extended International SMS coverage.

Test SMS Notify! API for free.


Short Code Text Messaging Compliance

Short code text messaging is an excellent way to reach your customer and consumer base with relevant and time-sensitive information because text messages have a sense of urgency compared with other methods of communication. But it is important to note that text messaging is a permission-based medium that requires the sender to obtain the recipient’s consent to send SMS to their handset. Because consumers pay to receive text messages, the wireless carriers regulate the industry and create rules for interacting with recipients through SMS. CTIA is the International Association for the Wireless Telecommunications Industry that monitors text messaging for the carriers and issues violation notices. Non-compliant text messaging can result in citations, suspension, or termination of your short code campaign. The CTIA published a Compliance Handbook, effective June 2012, which clarifies the industry compliance rules, opt-in, and mobile campaign deployment.

Call to Action

A call to action is is an opportunity for a business to successfully capture a mobile number and an invitation for a consumer to provide their cell phone number in order to subscribe to content. Several examples include on-site signage, print advertisements, or a web page. The wireless industry requires that a call to action contains five pieces of information including:

Product description and quantity

What will the recipient receive by providing their cell number? And how often? (e.g. Receive account alerts 2-3/month)

Program identification

What is the name of the business, or the text messaging initiative? (e.g. Dr. O’s Medical Alerts)

Opt-out instructions

Include the keyword in bold that recipients must text to stop receiving messages. (e.g. Text STOP to unsubscribe)

Message and data rates may apply

Customers should know that carriers may charge them for these text messages. (e.g. Message & Data rates may apply)

Links to privacy policy and terms and conditions

Dedicated short code users must create a privacy policy. Shared short code users can use the policy drafted by CDYNE for each shared short code. Terms and conditions must be posted online. (e.g. Privacy Policy and Terms & Conditions)

Opt-In: Even if You Already Have a Business Relationship

It’s worth mentioning here that existing business relationships and the purchase of opt-in lists do not automatically allow a company to send text messages to those mobile numbers. For example, if you already communicate with customers via email, you must still get their permission to receive text messages. Or if you collect mobile numbers during an online transaction or other method – this does not count as an opt-in. Automatic enrollment in multiple programs is not allowed, and the CTIA requires a dedicated opt-in for each program. The CTIA  Compliance Handbook outlines four examples for capturing opt-in. In all opt-in scenarios, consent to receive text messages must be clear and accurate at the time the mobile number is given.

  • Enter a phone number online,
  • Click a button on a mobile Webpage,
  • Send an MO message containing an advertised keyword, or
  • Sign up at a point-of-sale location


The reason behind all the rules and regulations is to eliminate unsolicited text messages, or SPAM. The CTIA Compliance Handbook defines unsolicited messages as, “All messages delivered before a user opts in or after a user receives confirmation of opt-out, and any message delivered in excess of the quantity advertised, are considered spam.”

For more information about the laws that address SPAM, read the FCC’s guide titled “Spam: Unwanted Text Messages and Email.”

CDYNE supports only the sending of opt-in text messages from the SMS Notify! API for both short codes and DIDs.  In an effort to ensure that all text messaging sent through CDYNE SMS Notify! API is conducted responsibly, please read the Responsible Use Guidelines.

Contact CDYNE for more information about short codes.

Test SMS Notify! API for free.


SMS Notify! API System Keywords

SMS Notify! API is a programming interface that provides connectivity to wireless carriers. It allows developers to build business applications to send and receive text messages using DIDs or short codes. DIDs are SMS-enabled 10-digit phone numbers (e.g., 757-544-9510), and short codes are 5- to 6-digit numbers (e.g. 55512). Here is a PDF document outlining the differences between each method. One important feature of SMS Notify! is the system keywords. When a person begins a text message with a system keyword and sends it to your DID or short code, SMS Notify! will automatically send a text message reply. System keywords and responses vary between DIDs and short codes as outlined below.

DID System Keywords


System Response:“Business Name”-SMS Notifications.Txt STOP to end.Msg&Data Rates may apply.”Business point of contact.”

  • The default business name is the name used to sign up for the SMS Notify! account. This may be updated by contacting CDYNE.
  • The business point of contact is two forms of contact including any combination of phone number, email, or website.

System Response: This provider is now blocked. Text back RESUME to unblock your number.

  • SMS Notify! API will block the recipient’s number from receiving messages until the recipient sends RESUME.
  • CDYNE will log the recipient STOP request including the license key, sending DID, and recipient’s phone number.
  • The STOP response occurs at the license key level. SMS Notify! will only block messages from that same license key to the recipient’s phone number.
  • Other license keys may send to the recipient’s phone number.

System Response: OK.

  • This will allow SMS Notify! to send messages to a recipient who previously sent a STOP command.
  • License Key with Assigned DIDs: The recipient can reply RESUME to any DID assigned to the license key that logged the original STOP request.
  • License Key without Assigned DIDs: The recipient must reply RESUME to the original DID assigned to the license key that logged the original STOP request.

Short Code System Keywords


System Response:“Business Name”: Reply STOP to cancel. Msg&Data Rates may apply. Msg Freq per acct setup. “Business #.”

  • The default business name and number is the name and number used to sign up for the SMS Notify! account. This may be updated by contacting CDYNE.
  • The HELP response for short codes are at the license key level so you can set up multiple custom HELP responses per short code.

System Response:“Business Name”: You have opted out and will no longer receive messages from this service. “Business #”

  • SMS Notify! API will block the recipient’s number from receiving messages until the recipient sends RESUME.
  • The STOP response occurs at the license key level. SMS Notify! will only block messages from that same license key to the recipient’s phone number.
  • The reply to French keywords is the standard English reply.

System Response: Welcome to “ProgramName”. Reply STOP to cancel. Reply HELP for help or call “ProgramContact”. Msg&Data rates may apply.  Msg freq per acct setup. Pwr’d by CDYNE.

  • Shared short code system messages will contain “Pwr’d by CDYNE.” Dedicated short code messages will not.

Contact CDYNE for more information about short codes.

Test SMS Notify! API for free.


Receiving SMS Messages with Short Code Keywords

A short code keyword is a unique one-word phrase that identifies a business, product or service. Keywords allow multiple  businesses to run unique campaigns on the same short code. Likewise, a business using a dedicated short code can differentiate communications with multiple keywords. For example, your dentist places a sign in the waiting room that says, “Text SMILE to 55512 to get appointment reminders.” In this example, “SMILE” is the keyword, and “55512” is the short code. By texting SMILE to short code 55512, the patient is opting in to receive appointment reminders. Using the same short code, the dental office may run a separate promotional offer. For example, “Text WHITE to 55512 for $25 off teeth whitening.” In this way, patients choose the interaction they wish to receive from their dentist. Communication with short codes and keywords give businesses great flexibility and responsiveness when engaging their customers, patients, or clients with text messaging. Here are guidelines and rules to consider when using keywords:

Select User Friendly Keywords

Keep it short – A short keyword is easy to remember.

Make it memorable – An easy to remember keyword will generate a better response.

Use a single word – SMS Notify! will match the entire message when checking for incoming keywords. If an incoming keyword is followed by any characters, a match will not be made.

SMS Notify! Incoming Keyword Rules

  • Only 1 instance of keyword per short code
  • Keyword cannot be a system keyword (e.g., STOP, HELP, ect.)
  • Keyword must be at least 3 characters long
  • Keyword cannot be a typical SMS response (e.g., sure, yes, thanks, monday)
  • Keywords are not case sensitive; ‘THIS’ is the same as ‘this’ and ‘ThIs’

Using PostBackURL to Capture Incoming Keywords

Developer’s can set up automated responses to incoming keywords using the SMS Notify! API PostBackURL system. When a keyword is assigned to your short code, CDYNE can also assign a URL or webpage you designate. Set your application to look for the variable SMSResponse=1, which is posted when a message is sent to your short code, or when a response to your outgoing message arrives. PostBackURL data is posted behind the scenes, and is not visible on your webpage. Program your application to capture the PostBackURL variables that are passed to your webpage from SMS Notify! API.

Contact CDYNE for more information about short codes.

Test SMS Notify! API for free.