Acme Company has several offices around the country. The company has deployed a VoIP network with Cisco Unified CallManager in a multisite centralized configuration but the is a requirement to place a call agent at some of the remote sites. Which IOS gateway feature should be deployed at the remote site to enable local call control？（）
- AGatekeeper multizone
- BCall Admission Control （CAC）
- CAutomatic Alternate Routing （AAR）
- DSurvivable Remote Site Telephony （SRST）
- ECisco Unified CallManager Express （CME）