Since you are an existing CMLink user, things will be slightly different. A Koodo rep will reach out to you shortly with a special offer, which will allow you to port your number over. 

At this point, it does not seem you will need to get a new SIM card, but I would suggest you to confirm with one of the Koodo reps. 

For more information, you can visit the following link. https://www.koodomobile.com/cmlink-en

As for your other question, there is no charge for receiving text messages from Canada, but you will need to pay for any data usage, texts, or calls being made from China. 

HI, I am from Hong Kong., my 14 yrs old son is using CMLink service at a boarding school in Vancouver ,  can I email someone or message to someone instead to switch him to Koodo?   He is too young to call your hotline for the switching.    Or do I have to call IDD from HK for this switching?    I hope I can just do the switching via email or messagning.  Hope someone can help.  Thank you!

Unfortunately, there is no way to switch over email or messaging. You will either need to sign up for a plan on the Koodo page or have your son go to one of the Koodo stores to sign up for the service. It would be extremely difficult to get it online unless you have a Canadian credit card and driver’s licence or SIN card to go through a credit check.

If that does not work, you may have a better chance having him switch over to Telus. You can either chat or give them a call for more details. https://www.telus.com/en/on/support/contact-us