Automated Attendant :
Callers are greeted with a series of menu prompts (e.g., press 1 for Customer Services, press 2 for Sales) for reaching the department or extension they desire.

Automated Call Distributor (ACD) :
Ensures calls are answered quickly and efficiently by routing inbound callers to group of employees with pooled extensions (i.e., support, sales, etc.).  ACDs are generally used by sales and support groups to improve service levels and increase group utilization.

Direct Inward Dial (DID) :
Provides company employees their own unique phone number so callers can reach them directly.

Music On Hold :
Callers listen to music while waiting on hold.

Promotion On Hold :
Allows your company to inform callers about key company promotions, procedures or value propositions while they wait on hold.

Interactive Voice Response (IVR) :
Allows callers to input and retrieve information from your company's computer database(s) via their touchtone telephone.  IVRs are typically used by sales and support teams to improve their service levels and reduce support costs for high call frequency tasks (e.g., order status).

Unified Messaging : 
Improves employee productivity by storing their email, fax, and voice messages in a single inbox accessible anytime anyplace via the phone, PC, Web or wireless device.

Toll Fraud Equipment :
A phone system monitor that reduces the risk of fraud and damage caused by hackers.

Voicemail :
Allows callers to leave personal messages if an extension is not answered.

Voice over IP (VoIP) :
Reduces toll charges by allowing company employee's to use the IP network their PC is are connected to for placing and receiving phone calls.  Also known as IP telephony or "VoIP".