It's important to note that this refers to the sounds, not the letters. Some letters represent multiple sounds, and some sounds are represented by multiple letters.
Here are the 24 consonant sounds:
* Stops: /p/, /b/, /t/, /d/, /k/, /g/, /ʔ/ (glottal stop)
* Fricatives: /f/, /v/, /θ/, /ð/, /s/, /z/, /ʃ/, /ʒ/, /h/
* Affricates: /tʃ/, /dʒ/
* Nasals: /m/, /n/, /ŋ/
* Liquids: /l/, /r/
* Glides: /w/, /j/