Aircall Help Center | SMS messaging requirements and best practices

When developing a text messaging strategy, businesses should have a clear understanding of their communication needs, their partners’ SMS distribution capabilities, and the legal restrictions that apply to messaging in different countries.

This article provides an overview of Aircall’s SMS capabilities and key best practices to help your business ensure compliant and effective text message communications.

Aircall SMS functionality

Aircall enables customers to engage with their clients through two-way SMS messaging, also known as Conversational SMS.

Aircall does not support automated or one-way SMS messaging, which is often used in marketing campaigns. If your business requires this functionality, please explore our supported third-party SMS solutions.

Anticipating your messaging requirements

Before implementing SMS communications, clearly define your messaging needs. The following factors will help determine the most suitable setup for your business. Please share these details with our Customer Success team to help us recommend the right solution.

Define your messaging needs

Category	Options
Messaging channel	Separate channel (dedicated numbers for messaging) / Complementary channel (numbers used for both voice and messaging)
Use case	Internal communications / External communications (marketing, sales, or support)
SMS outbound volume (per month)	Up to 500 / 501–1,000 / 1,001–5,000 / 5,001–10,000 / 10,001+
Inbound volume (per month)	Balanced (equal or within 10% of outbound) / Unbalanced (half of outbound) / Limited inbound volume
Number of users	Number of users per phone number requiring access to message-enabled lines

Note: The volumes above are for planning purposes and do not represent Aircall SMS limitations.

Local requirements and industry practices

Businesses should always ensure that their messaging activities comply with local laws and regulations. Requirements vary by country.

Important: Aircall strongly recommends consulting a qualified local legal adviser to ensure full compliance with national regulations and industry standards.

For example:

United States: Messaging phone numbers used for campaigns must be registered.
Canada and the United States: Toll-free numbers used for SMS must be verified.

Prohibited content and use cases

Aircall and its suppliers prohibit any content that is illegal, harmful, inappropriate, or misleading, even if permitted by law.

Examples of prohibited content

Hate speech, harassment, or incitement to violence
Phishing or fraudulent messages
Malware or viruses
Content designed to bypass carrier filters (e.g. “snowshoeing”)
Deceptive or high-risk marketing schemes (e.g. pyramid marketing, gambling, “get rich” offers)

Additional prohibited practices

Avoid using letter or number substitutions such as “Fr33” instead of “Free” or “S@ve” instead of “Save.”

Note: Messages using this style violate carrier codes of conduct. They may be blocked as spam and can result in suspension of your 10DLC campaign.

Important: 10DLC campaigns apply only to US numbers.

Messaging best practices

Opt-in

Recipients must consent to receive commercial text messages. The type of consent required depends on the message type:

Type of messaging	Consent type
Conversational	Implied when a two-way exchange occurs on a specific topic, especially if initiated by the customer.
Informational	Given when the recipient provides contact details to receive updates (e.g. through a website form).
Promotional	Must be given in writing, typically via an opt-in form, especially for marketing content with calls to action.

Tip: For promotional campaigns, set clear expectations about message frequency—especially if you plan to send more than five messages per month.

Opt-out

Customers must be able to stop receiving promotional messages. The opt-out process often includes instructions such as “Send STOP to opt out” or a link to an opt-out form.

When a recipient replies with an opt-out keyword (e.g. STOP, UNSUBSCRIBE, CANCEL), no further messages should be sent.
Most Aircall SMS-enabled numbers include opt-out functionality by default. Confirm this with our Customer Success team.
In the United States, responding with an opt-out keyword automatically blocks further messages from that number and sends a confirmation: “You have successfully been unsubscribed. You will not receive any more messages from this number. Reply START to resubscribe.”

Note: The automatic blocklist works at the number level only. If you send messages from multiple numbers, you must manually ensure recipients’ numbers are blocked across all numbers, or use a specialized Aircall partner.

Sender identification

Include clear business identification information in your messages. Depending on the country, this may be required either in the first message or in every message.

Message length and URLs

To help prevent carrier filtering, consider the following best practices:

Keep messages under 250 characters
Avoid URL shorteners (e.g. bit.ly, tinyurl)
Do not cycle domains or subdomains across messages
Avoid redirecting URLs that obscure the final destination website

SMS traffic whitelisting

Some countries restrict sending commercial messages outside business hours. In the United States, avoid sending texts to non-SMS-enabled numbers, as these will fail delivery and could lead to your number being blocked. You can verify numbers before sending messages using a lookup service such as numverify.com.

Cross-check numbers against Do-Not-Contact registries

Many countries maintain Do-Not-Contact or Do-Not-Disturb registries where individuals can opt out of receiving commercial communications. Always cross-check your contact lists against these registries before sending messages.

SMS restrictions

For more information on SMS compliance, rate limits, and regional restrictions, refer to the following articles:

Outside these regional rules, Aircall applies a standard limit of 10,000 messages per user per month (measured in message segments).

Note: This article provides general information and should not be considered legal advice. Always consult professional counsel for guidance on your specific situation.

This article provides an overview of Aircall’s SMS capabilities and key best practices to help your business ensure compliant and effective text message communications.

Aircall SMS functionality

Aircall enables customers to engage with their clients through two-way SMS messaging, also known as Conversational SMS.

Anticipating your messaging requirements

Define your messaging needs

Category	Options
Messaging channel	Separate channel (dedicated numbers for messaging) / Complementary channel (numbers used for both voice and messaging)
Use case	Internal communications / External communications (marketing, sales, or support)
SMS outbound volume (per month)	Up to 500 / 501–1,000 / 1,001–5,000 / 5,001–10,000 / 10,001+
Inbound volume (per month)	Balanced (equal or within 10% of outbound) / Unbalanced (half of outbound) / Limited inbound volume
Number of users	Number of users per phone number requiring access to message-enabled lines

Note: The volumes above are for planning purposes and do not represent Aircall SMS limitations.

Local requirements and industry practices

Businesses should always ensure that their messaging activities comply with local laws and regulations. Requirements vary by country.

Important: Aircall strongly recommends consulting a qualified local legal adviser to ensure full compliance with national regulations and industry standards.

For example:

United States: Messaging phone numbers used for campaigns must be registered.
Canada and the United States: Toll-free numbers used for SMS must be verified.

Prohibited content and use cases

Aircall and its suppliers prohibit any content that is illegal, harmful, inappropriate, or misleading, even if permitted by law.

Examples of prohibited content

Hate speech, harassment, or incitement to violence
Phishing or fraudulent messages
Malware or viruses
Content designed to bypass carrier filters (e.g. “snowshoeing”)
Deceptive or high-risk marketing schemes (e.g. pyramid marketing, gambling, “get rich” offers)

Additional prohibited practices

Avoid using letter or number substitutions such as “Fr33” instead of “Free” or “S@ve” instead of “Save.”

Note: Messages using this style violate carrier codes of conduct. They may be blocked as spam and can result in suspension of your 10DLC campaign.

Important: 10DLC campaigns apply only to US numbers.

Messaging best practices

Opt-in

Recipients must consent to receive commercial text messages. The type of consent required depends on the message type:

Type of messaging	Consent type
Conversational	Implied when a two-way exchange occurs on a specific topic, especially if initiated by the customer.
Informational	Given when the recipient provides contact details to receive updates (e.g. through a website form).
Promotional	Must be given in writing, typically via an opt-in form, especially for marketing content with calls to action.

Tip: For promotional campaigns, set clear expectations about message frequency—especially if you plan to send more than five messages per month.

Opt-out

Customers must be able to stop receiving promotional messages. The opt-out process often includes instructions such as “Send STOP to opt out” or a link to an opt-out form.

When a recipient replies with an opt-out keyword (e.g. STOP, UNSUBSCRIBE, CANCEL), no further messages should be sent.
Most Aircall SMS-enabled numbers include opt-out functionality by default. Confirm this with our Customer Success team.
In the United States, responding with an opt-out keyword automatically blocks further messages from that number and sends a confirmation: “You have successfully been unsubscribed. You will not receive any more messages from this number. Reply START to resubscribe.”

Note: The automatic blocklist works at the number level only. If you send messages from multiple numbers, you must manually ensure recipients’ numbers are blocked across all numbers, or use a specialized Aircall partner.

Sender identification

Include clear business identification information in your messages. Depending on the country, this may be required either in the first message or in every message.

Message length and URLs

To help prevent carrier filtering, consider the following best practices:

Keep messages under 250 characters
Avoid URL shorteners (e.g. bit.ly, tinyurl)
Do not cycle domains or subdomains across messages
Avoid redirecting URLs that obscure the final destination website

SMS traffic whitelisting

Cross-check numbers against Do-Not-Contact registries

SMS restrictions

For more information on SMS compliance, rate limits, and regional restrictions, refer to the following articles:

Outside these regional rules, Aircall applies a standard limit of 10,000 messages per user per month (measured in message segments).

Note: This article provides general information and should not be considered legal advice. Always consult professional counsel for guidance on your specific situation.