Information Technology Reference
In-Depth Information
Circuit Switched via PIMg
The PIMG provides connectivity and integration between Unity and PBXs. PIMGs sit directly between Unity and PBXs and emulate
digital or analog phones to connect with PBXs (it connects via a digital phone line), and use SIP to connect with Unity over an IP
network.
Because a PIMG connects to Unity over an IP network, it is no longer necessary to install a voice card in the Unity server to integrate
with a PBX, and it is even possible for a Unity server to be connected to a PIMG (and PBX) over an IP WAN.
MWI and SMDI
SMDI can be used over RS-232 to connect a PBX to a voicemail system (such as Unity). SMDI is an out-of-band signaling system,
which necessitates voice and signaling information being carried on separate paths.
When integrating PBXs and legacy voicemail systems, they can be connected using an RS-232 connection, and automatic number
identification (ANI) and Redirecting Dialed Number Identification Service (RDNIS) are used to indicate the calling party number and
the original intended recipient (the recipient of the voicemail message), respectively.
SMDI can be used to transmit information about call types, including direct calls and forwarded calls, about MWI on and off states,
and about error states. SMDI messages are comprised of ASCII characters and symbols.
SMDI Messages with Direct and Forwarded Calls
The format of SMDI messages with direct calls is as follows:
<CR><LF>MD md-num md-port fwd-type<0x20>src-num<0x20><CR><LF><^Y>
The components of this message are as follows:
■
<CR>:
A carriage return
■
<LF>:
A line feed
