Information Technology Reference
In-Depth Information
Note: Many VoIP deployments now connect to the PSTN using an Internet Telephony
Service Provider (ITSP) rather than a traditional TSP. In this case, the CME router relays the
voice call over a SIP trunk rather than an analog or digital circuit.
The CME router has now established two different “legs” of the call: one to the PSTN and
the other to the Cisco IP Phone. It stands in the middle, independently handling signaling
from both sides in two different formats. Unlike the first example, the CME router is now
a critical piece of the ongoing RTP audio flow. If it were to fail in the middle of the call,
the audio for the call would also fail.
A Match Made in Heaven: CME and CUE
CME is a fantastic, all-in-one call processing device, provided someone is there to answer
the phone. However, just like the full-blown CUCM, there are no built-in voicemail capa-
bilities. All that changes when CUE steps onto the stage. CUE is a voicemail system that
you can install into your CME router in one of two form factors: Internal Services Module
(ISM) or Service Module (SM). The ISM form factor installs internal to the CUE router
and uses solely flash memory for storage. The full SM form factor installs externally to the
router and uses a hard disk for storage. Because of this, it can hold roughly ten times as
much voicemail as the ISM form factor.
Cisco designed ISM and SM for the ISR G2 series of routers (1900, 2900, and 3900). They
are upgrades from the previous Advanced Integration Modules (AIM) and Network Mod-
ules (NM), shown in Figure 2-3 and Figure 2-4, which were used in the first-generation
ISR routers (1800, 2800, and 3800).
Figure 2-3
CUE AIM
Figure 2-4
CUE NM
 
 
Search WWH ::




Custom Search