Hong Kong (HK)

Locale name

Hong Kong

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

HK

Region

Asia

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.

454

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

+852

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.

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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.

Effective February 21, 2024, all customers can start using registered Alphanumeric Sender IDs with a hash (#) prefix, such as #twiliocorp, to send SMS messages to Hong Kong (see press release from the Office of the Communications Authority or OFCA). Please note that this does not impact SMS messages sent from Hong Kong domestic longcodes. To use Alphanumeric Sender IDs with a hash (#) prefix, you need to register it first by going on OFCA's website. After registering with OFCA, you need to register it with Twilio by following this link. 

Sending firearms, gambling, adult content, money/loan, political, religious, controlled substance, cannabis, and alcohol related content is strictly prohibited.

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, particular 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 Alphanumeric Sender IDs without a hash (#) prefix

There is no segregation between International and Domestic Traffic

Supported

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

Supported
Learn more and register via the Console

Supported
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

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.

18 days

N/A

UCS-2 support

Supported

Supported

Use case restrictions

For Alphanumeric Sender IDs without a hash (#) prefix, registration is only required on mobile operator China Mobile Hong Kong, while other Hong Kong mobile operators support dynamic Alphanumeric Sender IDs.

All customers can use registered Alphanumeric Sender IDs with a hash (#) prefix to send to all HK mobile operators starting on February 21, 2024.

The mobile operator China Mobile Hong Kong does not support dynamic Alphanumeric Sender ID and requires Sender ID pre-registration. Sending non-registered Sender ID to this network will result in delivery failure.


The enforcement of blocking unregistered Sender IDs in China Mobile Hong Kong  has been postponed from November 24, 2024, to a date before the end of Q1 2025. Further updates will be provided as soon as a more definitive date is available. Please Register an Alpha Sender ID in Hong Kong to avoid having your messages blocked. 

Best practices

Register your Alphanumeric Sender IDs without a hash (#) prefix with Twilio.

Additionally, in an effort to combat SMS spoofing and phishing attacks, the Office of the Communications Authority (OFCA) in Hong Kong now recommends all customers to register their Alphanumeric Sender IDs with a hash (#) prefix. We’ve updated our registration process to comply with this recommendation.

Use only registered Alphanumeric Sender ID when sending messages to mobile operator China Mobile Hong Kong and non-generic Alphanumeric Sender ID to the other Hong Kong mobile operators.

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

Supported

Not Supported

Not Supported

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

Supported

Supported

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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

Numeric Sender ID is not supported by mobile operators in Hong Kong and would be overwritten with either a generic Alphanumeric Sender ID or a random domestic Numeric Sender ID.

N/A

Best practices

N/A

Twilio will start blocking on the 24th of October of 2024  any traffic submitted to the network China Mobile from International Longcode Sender IDs. Please register an Alpha Sender ID in Hong Kong to avoid having your messages blocked. 

N/A