What are the disadvantages in cdma?

Disadvantages to CDMA are

Your handset can only be used with the provider that you got the phone from. Should your phone brake under contract but out of warranty, getting a new phone from the provider will automatically extend your contract another 2 years.

CDMA is limited to North America and a few other places, GSM is worldwide. If you like to travel oversea's, for the most part, leave your CDMA phone at home.

GSM phones can be unlocked meaning that they can be used with any GSM provider. If my GSM phone brakes, I can get a cheap replacement phone without having to extend my contract. When I travel oversea's, I can continue using my service, better yet, I can use a local sim card for the country I am in and make and receive calls at a much lower rate.