Most frequently asked questions from Clerk customers
How Does Clerk Free Trial Work?
Clerk is free to use with 10 SMS. You can use this plan for as long as you like as long as you are within that particular limit. Under the free plan, Clerk phone number is elastic and will be released every few weeks.
What if someone calls my Clerk phone number?
If your Clerk number is SMS Only, it only supports text messages. If someone tries to call your Clerk SMS only number by default the call will be dropped and nothing will happen.
We have a number of other add-ons that would allow you to either call forward to a different number or enable full voice capabilities.
What countries do you support?
We natively support the following countries:
  • 🇺🇸 United States
  • 🇨🇦 Canada
  • 🇬🇧 United Kingdom
The majority of other countries are also supported but would have to be enabled manually by the Clerk team. Please reach out to our support team with your requested number.
Can I Port My Toll-free Number To Use For Text Messaging?
Absolutely. Once you’ve ported your toll-free phone number into Clerk it will be enabled for sending and receiving SMS messages.
Is Clerk HIPAA and PHIPA Compliant?
Even though we strive to ensure the latest standards and security, we are not HIPAA and PHIPA compliant at this time but we are working on getting the certification.
When does my SMS limit reset?
SMS count resets on the first day of the month.
What is the character limit for SMS text messages?
The maximum number of characters per single message being sent to carriers depends on the encoding used, and the encoding used depends on the content of the message. Refer to our SMS Limits doc for a detailed breakdown.
What are the maximum file sizes for MMS messages for the major carriers in the US?
  • ATT: 1MB
  • Verizon: 1.5MB
  • Sprint: 2MB
  • T-Mobile: 1MB
The file sizes above will generally be passed along to the wireless carriers. However, due to differences in handsets, file types, and transcoding, we recommend you send attachments no larger than 5 MB to ensure the best chance of delivery.
Is there a way to block incoming SMS on my Clerk phone number?
Yes. Just add the phone number to the Do Not Disturb List.
Can I transfer my Clerk subscription to another Slack workspace?
Absolutely. Please reach out to the team at [email protected] and we will work with you to transfer your subscription to another slack workspace. There is a one time $25 fee associated with the transfer of your account.
Should I use SMS in threads or channels?
We've built Clerk to support a variety of Slack workflows. Enterprises with a large volume of text messages might prefer to use the thread SMS functionality where all inbound SMS go into a single "triage" channel. Internal support team can then triage the conversations and move them to individual channels should they choose to.
Small businesses or organizations that have a pre-defined set of contacts or vendors might want to use the direct channel functionality and separate SMS conversations into their own individual Slack channels.
What happens if I delete or archive a direct channel?
If a direct channel with a contact has been deleted or archived a new inbound message would get posted to your shared channel. You can choose to keep the conversation there or re-create the direct channel. On a new outbound message you can choose to send the message to the shared channel or create a brand new direct channel.

How do I stop Spam SMS?

SMS is really hard to filter as anyone can send you random spam messages. We are working on a filter and will release it in the next few months. In the meantime follow these steps to avoid spam.
  1. 1.
    You can use the "Do Not Disturb" feature to block the number permanently
  2. 2.
    You can reply "STOP" to the number & they will never send you unsolicited spam again. As it is illegal to send spam SMS without the receiver's consent.