China does not support alphanumeric Sender IDs. Instead, it's known as a “Signature,” which is added by the SMS provider at the beginning of messages delivered on long codes, like this: "[ChinaSMS]."
China is also blocking unregistered Sender IDs. Although Sender ID registration is permitted for local traffic, Bandwidth currently supports only international traffic. As such, Sender ID registration through Bandwidth is limited to international traffic only under the use of the generic sender "ChinaSMS", and it's only for international companies located outside of China for traffic destined to China.
Registration is required, and your Sender IDs must comply with the following requirements in order to mitigate the risk of traffic being blocked:
Examples of all types of messages to be sent
Type of traffic allowed:
By origin: International traffic only
By content: Transactional traffic only
Note: Due to the strict restrictions on messaging, local carriers may still block traffic.
If you’re a brand owner or applying for Sender ID registration, please open a ticket with the Bandwidth Compliance Team. Once you submit your request, the Compliance Team will review it and notify you as soon as your Sender ID is successfully registered.