Google Voicemail is free and doesn't charge. You can use google's voicemail in place of your carriers voicemail(check the supported carriers.) Like the previous user mentioned, there is a ten cent credit to your account when activated.
The feature that announces the caller and asks you if you want to accept or send to VM is called "Call Screening" and if you would like to turn that off, go to Settings>Calls and switch "call screening" to off.