Czech Republic (CZ)

Locale name

Czech Republic

ISO code
The International Organization for Standardization two character representation for the given locale.

CZ

Region

Europe

Mobile country code
A three digit code associated with the given locale and used in conjunction with a Mobile Network Code to uniquely identify mobile networks.

230

Dialing code
The dialing prefix used to establish a call or send an SMS from one locale to the given locale.

+420

Two-way SMS supported
Whether Twilio supports two-way SMS in the given locale.

Yes

Number portability available
Whether number portability is available in the given locale.

Yes

Twilio concatenated message support
Concatenation refers to the capability of splitting a message that is too long to be sent in one SMS into smaller pieces and then joining the pieces at the receiving end so that the receiver sees the message as one. 

Yes*
For certain sender ID types this may not be supported. Where messages are split and rejoined may vary based on character encoding.

Message length
How many characters can be sent given a particular message encoding before the message will be split into concatenated segments.

160 Characters

Twilio MMS support
Multimedia Messaging Service (MMS) provides a standards-based means to send pictures and video to mobile phones.

Converted to SMS with embedded URL

Sending SMS to landline numbers
How Twilio handles an SMS message destined for landline telephone number.

You cannot send SMS to a landline destination number: the Twilio REST API will throw a 400 response with error code 21614, the message will not appear in the logs, and the account will not be charged.

Compliance considerations
Twilio strongly encourages customers to review proposed use cases with qualified legal counsel to make sure that they comply with all applicable laws. This table lists some general best practices.

Sender ID Compliance

Sender ID Registration is required in the Czech Republic for networks T-Mobile and O2. Unregistered Sender IDs will be overwritten with a generic Alphanumeric Sender ID outside of the Twilio platform and delivery will be attempted on a best-effort basis only.

The enforcement of complete blocking of unregistered Sender IDs in the Czech Republic for networks T-Mobile and O2 is on July 14, 2025. Twilio highly recommends sending from a registered Alphanumeric Sender ID to avoid having your messages blocked.

Delivery to M2M Numbers

Message delivery to M2M numbers is on best effort basis only.

Additional Phone Numbers and Sender ID Guidelines

Twilio strongly encourages customers to review proposed use cases with qualified legal counsel to make sure that they comply with all applicable laws. The following are some general best practices:

1. Get opt-in consent from each end-user before sending any communication to them, particularly for marketing or other non-essential communications.
2. Only communicate during an end-user’s daytime hours unless it is urgent.
3. SMS campaigns should support HELP/STOP messages, and similar messages, in the end-user’s local language.
4. Do not contact end-users on do-not-call or do-not-disturb registries.

Operator network capability
Whether mobile operators in the given country support the feature.

Required for T-Mobile and O2

There is no segregation between International and Domestic Traffic

Not Supported for T-Mobile and O2

Supported for the rest of Czech Republic networks

Twilio supported
Whether Twilio supports the feature for the given country.

Supported
Learn more and register via the Console

Not Supported for T-Mobile and O2 networks

Supported for the rest of Czech Republic networks

Learn more

Sender ID preserved
In some countries sender IDs for certain sender types are not preserved and are changed for compliance and/or deliverability reasons. In these countries mobile subscribers will see a different ‘from sender ID’ than the one sent by you.

Yes

Yes for the networks that Dynamic Alphanumeric is supported

Provisioning time
Provisioning is the process of getting the sender ID approved and registered with mobile networks (depending on country requirements). Provisioning time is how long this process takes in the given country.

3 weeks

N/A

UCS-2 support

Supported

Supported

Use case restrictions

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The Czech Republic networks T-Mobile and O2 require Sender ID registration. We advise Twilio's customers to register an Alpha Sender ID in the Czech Republic for full country coverage.

Best practices

N/A

Sender ID Registration is required for the Czech Republic networks T-Mobile and O2. Delivery via Dynamic Alphanumeric Sender ID will be attempted on a best-effort basis. The Sender ID will be overwritten with a generic Alphanumeric Sender ID outside the Twilio platform.

Operator network capability
Whether mobile operators in the given country support the feature.

Supported

Not Supported

Supported

Twilio supported
Whether Twilio supports the feature for the given country.

Supported

Supported

Not Supported

Sender ID preserved
In some countries sender IDs for certain sender types are not preserved and are changed for compliance and/or deliverability reasons. In these countries mobile subscribers will see a different ‘from sender ID’ than the one sent by you.

Yes

No

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Provisioning time
Provisioning is the process of getting the sender ID approved and registered with mobile networks (depending on country requirements). Provisioning time is how long this process takes in the given country.

N/A

N/A

N/A

UCS-2 support

Supported

Supported

N/A

Use case restrictions

N/A

N/A

N/A

Best practices

N/A

Sender ID Registration is required for the Czech Republic networks T-Mobile and O2. Delivery via International Long Codes will be attempted on a best-effort basis. The Long Code will be overwritten with a generic Alphanumeric Sender ID outside the Twilio platform.

N/A