Choose an SMS Sending Number

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Please note that only account Owners and Admins will have the ability to add/manage sending numbers.

When you start using Klaviyo to send SMS messages, you will automatically be assigned a sending number. This is the number from which your text messages will be sent, as well as the number that new subscribers will text to confirm their subscription.

That said, you may want to change this number. Klaviyo provides several different options for you to lease on a monthly basis, which are outlined in this guide.

Sending Number Options

By default, Klaviyo will provide you with a free long number (1-XXX-XXX-XXXX). 

Do not delete your first free long number, as any other long number will cost money.

To change your sending number, navigate to Account > Settings > SMS. Under Sending Numbers, click Additional Numbers. You can select either Request Additional Numbers or Port an Existing Number from the resulting dropdown menu.


If you select Request Additional Numbers, you will be provided with the following options:

  • Long number (1-XXX-XXX-XXXX)
    When you select this option, you will then be prompted to select the number of long numbers you would like (up to nine). You will receive a new long number immediately upon requesting it.
  • Toll-free number (1-800-XXX-XXXX)
    When you select this option, you will then be prompted to select the number of toll-free numbers you would like (up to nine). You will receive a new toll-free number immediately upon requesting it.
  • Short code (XXX-XX)
    When you select this option, you will initiate the process of leasing a short code. We do not currently support shared short codes, meaning your short code will be unique to your business. When you request a short code, you will see your request move to a pending state and will receive an email from a Klaviyo representative regarding next steps.
  • Vanity short code (XXX-XX)
    When you select this option, you will see your request move to a pending state and will receive an email from a Klaviyo representative regarding next steps. You will then work with this representative to specify which numbers you would like included in your short code, provided the number is available.

When you have more than one number in your account, different SMS subscribers may receive texts from different numbers. Once someone has received a text from your business, Klaviyo will continue to use that number to send to that profile as long as it remains associated with your account. That way, subscribers aren't receiving texts from multiple different numbers for the same business.

Porting Over an Existing Number

If you are migrating over from another SMS sending service and you have an existing short code or long number that you would like to use to send text messages, select Port an Existing Number from the Request Additional Numbers dropdown.


Next, you will see a modal confirming that you would like to submit a port request. To confirm this request, select Submit Port Request, and you can expect to be contacted by a Klaviyo representative. We can port over short codes, toll-free, and long numbers. However, we cannot port over shared short codes. If you were previously sending from a shared short code, you will instead need to request a brand new number.

SMS Sending Speeds

Below, we've outlined the major differences between long numbers, short codes, and toll-free numbers.

Number Type Sending Speed Price per Month Time to Provision
Long number  1 msg/second First one is free, then $1/month Immediate
Short code  100+ msg/second

$1,300/month (random)

$1,800/month (vanity*)

Plus additional throughput costs

10–15+ week application process

Throughput increase takes ~1 week

Toll-free number  3–150 mgs/second


Plus additional throughput costs


Throughput increase takes ~1 week

*Vanity is the only option that allows you to specify the number, pending availability.

How to Choose the Right Number for Your Business

There are pros and cons associated with each type of number outlined above. To help you choose what's right for you, we've outlined some recommendations for each number type.

Long Number

If you're just starting out and would like to test to see if SMS is a channel you would like to invest in, we recommend starting with the free long number provided. This allows you to explore starting an SMS program with a very low financial commitment. Do not delete the free number provide; all additional long numbers will cost $1/month. If you only use this type of number, then for every 200 profiles who opt into SMS marketing from your business, we suggest adding a long number.

Another benefit of a long number is that you can start sending immediately — no need to fill out an application and wait weeks to be approved. Note that carriers will sometimes filter SMS messages from long numbers. If you experience this issue, check out Improving SMS Deliverability when Using Long Numbers. 

Short Code

If you have already established an SMS strategy and know for certain that this is a channel you would like to invest in, short codes are your best option. Short codes allow you the flexibility to send quickly to a large group of subscribers, which is a benefit if you have an existing SMS subscriber base and/or are migrating over from a previous SMS provider. Further, short codes are subject to less filtering from wireless carriers than long numbers. 

Short codes are also the only option that allows you to specify which number you're provisioned, so if brand recognition is very important to your business, this is another benefit.

While the application process for a short code can take several weeks, if you are certain this is a channel that you are going to use heavily, it is likely worth the wait.

Toll-Free Number

A toll-free number is similar to a long number, but it is more obvious that it's coming from a business because it's a toll-free number. Likewise, the benefits are similar: you can start sending immediately and it is a relatively low financial investment. The main distinction is that you can send more messages at once. 

Unlike long numbers, one toll-free number per account can also be verified. This can help increase deliverability, with more texts making it to your subscribers’ phones.

If you're somewhere in between starting from scratch with SMS and already having a substantial subscriber base, this is a good option for you. If you do decide to use this type of number to increase your throughput, note that this will not apply for any MMS messages, as toll-free numbers can't send multimedia text messages. 

Manage Your SMS Numbers

You can add up to 400 numbers in batches of no more than 20 to your Klaviyo account by clicking Request Additional Numbers. If you need more than 400 numbers, reach out to our Support Team.

If you later decide that you no longer need a number, you can release it by clicking the settings dropdown beside the number and selecting Release Number.


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