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Documents Required and Instructions to Register Your Alphanumeric Sender ID for HKAB, Government and Telecoms related Sender IDs in Hong Kong.

Before we begin

Effective December 28, 2023, banking customers must start using registered Alphanumeric Sender IDs with a hash (#) prefix, such as #twiliocorp, to send SMS messages to Hong Kong. Please note that this does not impact SMS messages sent from Hong Kong domestic long codes. To use Alphanumeric Sender IDs with a hash (#) prefix, you need to register it first with HKAB (see here to contact HKAB). After registering with HKAB, you need to register it with Twilio using the console.

This article outlines the documentation requirements for a pre-registration in Hong Kong.


To register your Alphanumeric Sender ID, the Hong Kong network operators require that you provide the following documents: 

  • Letter of Authorisation (LOA)-LOA to RSSP CITIC
  • Letter of Authorisation (LOA)-LOA to RSSP PCCW
  • Letter of Authorisation (LOA)-LOA to RSSP SmarTone
  • Letter of Authorisation (LOA)-LOA to China Mobile
  • Letter of Authorisation (LOA)-LOA to Twilio
  • Business Licence
  • Proof of registration that the Sender ID with # has been registered with HKAB

To get you up and running as quickly as possible, please fill out the document completely and accurately and provide any other required information. Use the examples provided for guidance. Note that mobile network carriers are very strict about the details! We highly recommend that you download the examples (hit right click, and select 'Save Image As...') and do a side by side comparison when you are filling out the documents.

Once you have downloaded the forms, follow these general instructions: 

  1. Fill in the yellow highlighted fields—completely replace each field with your own information. If a field is not highlighted, don’t change it.
  2. All LOAs to CITIC,PCCW,SmarTone and China Mobile have the same format with the only difference being who it is addressed to.
  3. If you have questions on how to fill in the required fields, refer to the annotated examples we provided for each field. 
  4. Have the documents signed by an authorised signatory of the Sender.
  5. In the yellow highlighted fields, add the Sender’s letterhead and/or logo, and sign where indicated.
  6. Upload the forms to the console.

LOA to RSSP CITIC,PCCW,SmarTone and China Mobile

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LOA to Twilio

Screenshot 2023-11-21 at 12.26.25.pngScreenshot 2023-11-21 at 12.41.27.png

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