CUCM Digit Manipulation CCSP Training Institute in New Delhi

Network Bulls
www.networkbulls.com
Best Institute for CCNA CCNP CCSP CCIP CCIE Training in India
M-44, Old Dlf, Sector-14 Gurgaon, Haryana, India
Call: +91-9654672192

Digit manipulation is often used to change calling-party numbers for caller ID purposes on
outgoing PSTN calls. Digit manipulation is also used to strip public switched telephone
network (PSTN) access codes before extending calls to the PSTN. Other uses of digit
manipulation involve expanding or modifying abbreviated dialing options. Inbound calls
from the PSTN may be ten digits in length, whereas the internal dial plan is only four or
five digits. These inbound calls would need to have the E.164 PSTN numbers converted
to the internal dial plan, which could be significantly smaller. It is normally required to
manipulate the calling-party (initiator) and called-party (destination) numbers when
routing a call to the PSTN. The PSTN access code needs to be stripped from the called
number before sending it out to PSTN. Most organizations use the number 8 or 9 as the
access code to the PSTN. The calling-party number also needs to be changed from the
abbreviated internal extension number to a full E.164 PSTN number to allow for easier
redial.
CUCM Digit Manipulation Overview
In Figure 12-1, an IP phone with extension 1002 calls a phone on the PSTN with a phone
number of 408 555-111. The user at extension 1002 must first dial a PSTN access code of
9 to direct a call to the PSTN. It is important to strip the 9 from the called number before
sending the call to PSTN; otherwise, the PSTN switch will not be able to route the call, and
the user will receive a reorder tone because no numbers on the PSTN in North America
begin with a 9 (except for 911 for emergency call routing). The calling-party number needs
to be expanded to a full PSTN number so that the PSTN user can see the proper, routable
caller ID of 706 555-1002, and not the extension of 1002, which is not routable on the
PSTN. This functionality will provide proper caller ID, which can be used by a variety
of features.
Table 12-1 displays some often used digit manipulation requirements and the method in
which they are handled in CUCM.
NOTE In some countries, the calling-party number must be set to the correct PSTN
number of the used PSTN subscriber line or trunk.
CUCM Digit Manipulation 285
Figure 12-1 Digit Manipulation Overview
Table 12-1 Digit Manipulation Methods
Requirement Call Type Method
Expand calling-party
directory number to full
E.164 PSTN number
Internal to PSTN Use calling-party’s external phone number mask.
The calling-party transformation in route pattern
or route list provides additional manipulation.
Strip PSTN access code Internal to PSTN Use digit stripping in the route pattern or route
list.
Expand abbreviated
number
Internal to internal Use called-party transformation in the translation
pattern.
Convert E.164 PSTN
called-party directory
number to internal number
PSTN to internal Use called-party transformation in the translation
pattern, or use significant digits.
Expand endpoint directory
numbers to accomodate
overlapping dial plan
Internal to internal
PSTN to internal
Use called-party transformation in the translation
pattern.
Cisco IP Phones
CCM1-1
SIP Third-Party
IP Phone
CCM2-1
T1/E1
Off-Net Calls
Local
Gateways
On-Net Off-Net
Calling 1002 1 706 555-1002
Called 9.1408-555-1111 1 408 555-1111
IP IP
e
1002
DID:
1 706 555-1001
PSTN
1 408 555-1111
V
V
286 Chapter 12: Digit Manipulation
Figure 12-2 illustrates an internal caller dialing a PSTN number using a PSTN access code
9 followed by the 11-digit PSTN number, where the following digit manipulations occurs:
1. CUCM discards the digit 9 before routing the call to the PSTN.
2. The internal extension calling-party number is expanded to the full 11-digit PSTN
number.
Simple called and calling-party transformations are used in the PSTN route list at the route
group level to achieve these two objectives. The calling-party transformation is often
dependent on the external phone number mask configuration on the directory number (DN).
Figure 12-2 Outgoing Call to PSTN
Figure 12-3 illustrates an incoming PSTN call to an internal phone, which is routed as
follows:
1. The PSTN phone calls the full E.164 number of the destination; the call is received
by the PSTN gateway with ten digits. Digit manipulation occurs on the gateway or
on CUCM to convert the full E.164 number to the internal dial plan. The gateway
configuration in CUCM is the easiest place to manipulate the incoming digits.
2. The destination DN can also be converted using a translation pattern that matches the
digits received from the provider. Translation patterns are not necessary to change the
incoming E.164 number to an internal directory number unless the incoming number
does not map directly or additional digit manipulation is required. To make it easier for
the IP phone user to call back the number, the calling-party transformation mask of the
translation pattern can be used to insert 91 to the caller’s number. This step is optional
because the IP phone user can always edit the number and manually add access code
9 and possibly the long-distance code 1 before calling back the PSTN number.
3. The IP phone receives the call, and the call is listed in the Received Calls menu.