Do I need to add any number to Unicom's home phone to send messages to the mainland in Hong Kong?

Under the roaming function of Hong Kong, Macao and Taiwan, Unicom users can roam to Hong Kong to make mainland calls as follows:

1. Call Hong Kong domestic mobile phone: 0086+ mobile phone number;

2. Call domestic fixed telephone or PHS: 0086+ area code (go to 0)+ telephone number;

Send short messages to Chinese mainland when roaming in Hongkong. Enter the number of the other party directly in the sending format, and then press the key to send.