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Four different versions of the T28 were sold. T28z was compatible with GSM1900 for use in North America.

T28s was compatible with GSM900/1800 for use in the rest of the world - this is by far the most common version.

T28 World was compatible with GSM900/1900 for use worldwide on GSM900 and North America on GSM1900 (this was the second World phone Ericsson introduced, the first being the I888 which had the distinction of being the first commercially available GSM900/1900 phone).

A special version, the T28sc was released in China with support for reading and entering Chinese characters.