What are the countries restrictions in Vietnam for SMS ?

The supported and non supported features and for SMS in Vietnam are the following : 

1) Handset delivery receipts are not reliable. In fact, All Vietnam operators do not support handset Delivery Receipts. Some routes generate network Delivery Receipt, therefore a 'positive Delivery receipt' does not necessarily mean the message was received on the handset.

2) Dynamic Sender ID is not supported.

3) Unicode is supported.

4) Concatenated Messages are supported.