You already spent so much money.
There’s an open source solution out there called Asterisk (http://www.asterisk.org) you may want to look into that could have very easily handled that for you.
Telephony Services:
Voicemail System
Password Protected
Separate Away and Unavailable Messages
Default or Custom Messages
Multiple Mail Folders
Web Interface for Voicemail Checking
E-mail notification of Voicemail
Voicemail Forwarding
Visual Message Waiting Indicator
Message Waiting Stutter Dialtone
Auto Attendant
Interactive Voice Response
Overhead Paging
Flexible Extension Logic
Multiple Line Extensions
Multi-Layered Access Control
Direct Inward System Access
Directory Listing
Conference Bridging
Unlimited Conference Rooms
Access Control
Call Queuing
ADSI Menu System
Support for Advanced Telephony Features
PBX Driven Visual Menu Systems
Visual Notification of Voicemail
Call Detail Records
Local Call Agents
Remote Call Agents
Protocol Bridging
Provides seamless integration of technologies
Offers a unified set of services to users regardless of connection type
Allows interoperability of VoIP systems
Call Features:
Music on Hold
Music on Transfer
Flexible mp3 based system
Volume Control
Random Play
Linear Play
Call Waiting
Caller ID
Caller ID Blocking
Caller ID on Call Waiting
Call Forward on Busy
Call Forward on No Answer
Call Forward Variable
Call Transfer
Call Parking
Call Retrieval
Remote Call Pickup
Do Not Disturb
Scalability:
TDMoE
Allows Direct Connection of Asterisk PBX
Offers Zero Latency
Uses Commodity Ethernet Hardware
Voice over IP
Allows for Integration of Physically Separate Installations
Uses commonly deployed data connections
Allows a unified dialplan across multiple offices
Voice over IP Interoperability:
Asterisk provides transparent bridging between Voice over IP protocols and traditional telephony equipment. In addition, Asterisk can transfer calls from one system to another via the Inter Asterisk Exchange protocol.
Inter-Asterisk Exchange (IAX)
H.323
Session Initiation Protocol (SIP)
Media Gateway Control Protocol (MGCP)
Traditional Telephony Interoperability
Robbed Bit Signaling Types
FXS and FXO
Loopstart
Groundstart
Kewlstart
E&M
E&M Wink
Feature Group D
PRI Protocols
4ESS
Lucent 5E
DMS100
National ISDN2
EuroISDN
BRI (ISDN4Linux)
Codec Support
GSM
G.729 (available through purchase of commercial license(s))
G.723.1 (pass through)
Linear
Mu-Law
A-Law
ADPCM
ILBC
LPC-10
MP3 (decode only)