Yes. Normally only the master earbud's microphone works during calls when you use both sides. If you'd like to use the left earbud only when making calls, only take the left earbud out of the charging case and close the charging case cover, connect "Spirit X2-L" to use it.
If you are using both earbuds for a call and then put one side in the charging case:
- Close the case to use the other earbud, there will be a break during this process. The call will be resumed after 3-5 seconds.