In a Cisco Unified Communications Manager design where +E.164 destinations are populated in
directory entries, which call routing practice is critical to prevent unnecessary toll charges caused

by internal calls routed through the PSTN?

A.
forced on-net routing

B.
automated alternate routing

C.
forced authorization codes

D.
client matter codes

E.
tail-end hop-off

Explanation:
It is not uncommon for the dialing habits for on-net/inter-site and off-net destinations to use the
same addressing structure. In this case the call control decides whether the addressed endpoint,
user, or application is on-net or off-net based on the dialed address, and will treat the call as onnet or off-net, respectively.
Figure 14-4 shows an example of this forced on-net routing. All four calls in this example are
dialed as 91 plus 10 digits. But while the calls to +1 408 555 2345 and +1 212 555 7000 are really
routed as off-net calls through the PSTN gateway, the other two calls are routed as on-net calls
because the call control identifies the ultimate destinations as on-net destinations. Forced on-net
routing clearly shows that the dialing habit used does not necessarily also determine how a call is
routed. In this example, some calls are routed as on-net calls even though the used PSTN dialing
habit seems to indicate that an off-net destination is called.
Figure 14-4 Forced On-Net Routing
Forced on-net routing is especially important if dialing of +E.164 destinations from directories is
implemented. In a normalized directory, all destinations are defined as +E.164 numbers,
regardless of whether the person that the number is associated with is internal or external. In this
case forced on-net routing is a mandatory requirement to avoid charges caused by internal calls
routed through the PSTN.
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab09/clb09/dialplan.html