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Implementing Dial Plans on Voice Gateways
Configuring PathSelection
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Call Routing and Path Selection
Relies on dial peers
Route to
TDM
IP Cisco IOS associates one dial peer to each call leg
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Matching Dial Peers
Cisco Unified CM**
PBX
PSTN
Cisco Unified
CME*/SRST
IP Phone
Analog
Phone
H.323
Gateway
IP
IP
POTSVoIP
VoIPPOTS
POTS POTS
IncomingCall Leg
OutgoingCall Leg
IncomingDial peers
OutgoingDial peers
1
2
3
Gateway
1
2
3
Gateway
withCisco
UnifiedCME*
**Unified CM = Cisco UnifiedCommunications Manager
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Digit-by-Digit Signaling
dial-peer voice 90 potsdestination-pattern 9Tport 0/0/0:23dial-peer voice 90110 potsdestination-pattern 9011Tport 0/0/1:23
User dials90114989123456.
0/0/
0
0/0/1
PSTN
InternationalLong Distance
Carrier
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Destination Pattern Matching
dial-peer voice 1 potsdestination-pattern 555port 0/0/0:23dial-peer voice 2 potsdestination-pattern 555....port 0/0/1:23
User dials 5551234.
0/0/
0
0/0/1
WAN
PSTN
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Inbound dial-peer matching:
Called number (DNIS) with incoming called-number
Calling number (ANI) with answer-address
Calling number (ANI) with destination-pattern
For POTS: voice-port matches with dial-peerport
Still no match: default dial peer 0 is used
Outbound dial-peer matching:
Gateway tries to match called number (DNIS) with destination-pattern
If multiple matches are found, the lowest preference wins.
If equal preferences are found, a random dial peer is chosen.
Matching Inbound and Outbound DialPeers
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destination-pattern [+]string[T]
router(config-dial-peer)#
Defines the destination pattern of a dial peer that will be used during
outbound dial-peer matching
incoming called-number [+]string[T]
router(config-dial-peer)#
Specifies the incoming called number that will be used during
inbound dial-peer matching
answer-address [+]string[T]
router(config-dial-peer)#
Specifies the incoming calling number will be used during inbound
dial-peer matching
Call Routing and Path SelectionCommands
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direct-inward-dial
router(config-dial-peer)#
Uses the inbound POTS DNIS to match the outbound dial peer (usuallyrequired for any DID PSTN trunk)
Used to prevent two-stage dialing
Call Routing and Path SelectionCommands (Cont.)
preference [0-9]
router(config-dial-peer)#
Specifies the preference of a dial peer; lower number = higher priority,default=0
no dial-peer outbound status-check pots
router(config)#
Disables status checking of outbound POTS dial peers during call setup;always includes dial peer in call routing, even if POTS status is down;useful for some ISDN links
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Matching Hunt Group Dial Peers
Longest match
Explicit preference
Random selection
Least recent use
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Best Practices
Default POTS dial peer with the direct-inward-dial attribute
Provide Cisco Unified Communications Manager redundancy
PSTN
Cisco Unified CM 110.10.10.2
Cisco Unified CM 210.10.10.3
dial-peer voice 1 potsincoming called-number .direct-inward-dial
dial-peer voice 100 voippreference 1destination-pattern 1...session target ipv4:10.10.10.2
dial-peer voice 101 voippreference 2
destination-pattern 1...session target ipv4:10.10.10.3
Indicates the primaryCisco Unified CM cluster
Indicates the secondaryCisco Unified CM cluster
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Path Selection Strategies
Call routing and path selection to route PSTNcalls over the cheapest possible path
Digit manipulation to support PSTN fallback
Tail-end hop-off (TEHO)
Call routing and path selection to route intersitecalls over WAN links with PSTN fallback
Digit manipulation to route calls over the WANor PSTN
Toll bypass
Call routing and path selection for intersite calls
Digit manipulation to support site-code dialingSite-code dialing
Dial Plan ComponentsPSTN Requirement
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Site-Code Dialing and Toll Bypass
Site codes are assigned to sites.
Users dial + to reach a user in aspecific site.
Site codes should be in a single range, if possible(e.g., 8XX).
The calling number should also include the site code of the callingparty.
This can be done via digit manipulation.
Easy way to solve overlapping numbering plan issues.
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Toll Bypass Example
IP WAN
PSTNPhone2-1
3001Phone2-2
3002
WAN is thepreferred path with
preference 1.
1
dial-peer voice 21 voip
destination-pattern 2...
preference 1
session-target ipv4:192.168.1.1
dial-peer voice 22 pots
destination-pattern 2...
prefix 14085552
preference 2
port 0/0/0:23
The PSTN pathis used if theWAN path isnot available.
2San Jose Austin
Phone1-12001
Phone1-22002
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Site-Code Dialing and Toll BypassExample
IP WAN
PSTNPhone1-1
2001Phone1-2
2002Phone2-1
2001Phone2-2
2002
User dials 8012001.
1
San JoseSite Code: 801
AustinSite Code: 802
R3R1
dial-peer voice 801 voipdestination-pattern 801.
session target ipv4:10.10.0.2
10.10.0.2 10.10.0.1
dial-peer voice 802 voipdestination-pattern 802.session target ipv4:10.10.0.1
Phone1-1 rings.Calling number:
8022002
2
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Tail-End Hop-Off
Extends the concept of toll bypass
Uses the WAN for PSTN calls as much as possible
Uses PSTN breakouts closest to the final PSTN destination
Uses PSTN paths as possible backup
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TEHO Scenario
IP WAN
Phone1-12001
Phone1-22002
Phone2-12001
Phone2-22002
San Jose Austin
R1 R3
4085550101
User dials914085550101.
1
Call is routed to SanJose via the WAN.
2
The San JosePSTN phone rings.
4
DID: 408555XXXX DID: 512555XXXX
PSTN
Local San Josegateway is used asthe PSTN breakout.3
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Configuring Site-Code Dialing andToll Bypass
1. Configure voice translation profiles for VoIP intersite routing.
2. Define dial peers for VoIP intersite routing.
3. Configure voice translation rules and profiles for PSTN backuprouting.
4. Define dial peers for PSTN intersite routing.
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IP WAN
PSTNPhone1-1
2001Phone1-2
2002Phone2-1
2001Phone2-2
2002
R1 R3
Users should beable to reach othersites via site codes.
If WAN fails, thePSTN path should
be used.
10.10.0.1 10.10.0.2
San JoseSite code: 801
ext: 2XXX
AustinSite code: 802
ext: 2XXX
Site-Code Dialing and Toll BypassScenario
DID: 408555XXXX DID: 512555XXXX
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IP WAN
PSTNPhone1-1
2001Phone1-2
2002Phone2-1
2001Phone2-2
2002
San JoseSite code: 801
ext: 2XXX
AustinSite code: 802
ext: 2XXX
R1 R3
10.10.0.1 10.10.0.2
voice translation-rule 1
rule 1 /^2/ /8022/
voice translation-rule 2
rule 1 /^8022/ /2/
voice translation-profile intersite-out
translate calling 1
voice translation-profile intersite-in
translate called 2
voice translation-rule 1
rule 1 /^2/ /8012/
voice translation-rule 2
rule 1 /^8012/ /2/
voice translation-profile intersite-out
translate calling 1
voice translation-profile intersite-in
translate called 2
Step 1: Configure Voice TranslationRules and Profiles for Intersite Routing
DID: 408555XXXX DID: 512555XXXX
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Step 2: Define Dial Peers for VoIPIntersite Routing
IP WAN
PSTNPhone1-1
2001Phone1-2
2002Phone2-1
2001Phone2-2
2002
10.10.0.1 10.10.0.2
dial-peer voice 8011 voip
destination-pattern 8012...
incoming called-number 802
session-target ipv4:10.10.0.1
translation-profile incoming intersite-in
translation-profile outgoing intersite-out
dial-peer voice 8021 voip
destination-pattern 8022...
incoming called-number 801
session-target ipv4:10.10.0.2
translation-profile incoming intersite-in
translation-profile outgoing intersite-out
San JoseSite code: 801
ext: 2XXX
AustinSite code: 802
ext: 2XXX
R1 R3
DID: 408555XXXX DID: 512555XXXX
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Step 3: Configure Voice Translation Rulesand Profiles for PSTN Intersite Routing
IP WAN
PSTNPhone1-1
2001Phone1-2
2002Phone2-1
2001Phone2-2
2002
R1 R3
10.10.0.1 10.10.0.2
voice translation-rule 3
rule 1 /^8012/ /14085552/
voice translation-profile 801PSTN
translate called 3
voice translation-rule 3
rule 1 /^8022/ /15125552/
voice translation-profile 802PSTN
translate called 3
San JoseSite code: 801
ext: 2XXX
AustinSite code: 802
ext: 2XXX
DID: 408555XXXX DID: 512555XXXX
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IP WAN
PSTNPhone1-1
2001Phone1-2
2002Phone2-1
2001Phone2-2
2002
R1 R3
10.10.0.1 10.10.0.2
dial-peer voice 8012 pots
destination-pattern 8012...
port 0/0/0:23
preference 1
translation-profile outgoing 801PSTN
dial-peer voice 8022 pots
destination-pattern 8022...
port 0/0/0:23
preference 1
translation-profile outgoing 802PSTN
San JoseSite code: 801
ext: 2XXX
AustinSite code: 802
ext: 2XXX
Step 4: Define Dial Peers for PSTNIntersite Routing
DID: 408555XXXX DID: 512555XXXX
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Outbound Site-Code Dialing Example
IP WAN
PSTN
voice translation-rule 1
rule 1 /^2/ /8022/voice translation-profile intersite-out
translate calling 1
dial-peer voice 8010 voip
destination-pattern 8012...
session-target ipv4:10.10.0.1
translation-profile outgoing intersite-out
1
2
ANI
DNIS
80220012001
80120018012001OutgoingIncoming
ANI
DNIS
31255520012001
140855520018012001
OutgoingIncoming
408-555-2001 312-555-2001
Site code: 802Site code: 801
1
2R1
10.10.0.1R3
voice translation-rule 3rule 1 /^8012/ /14085552/
voice translation-profile 801PSTN
translate called 3
dial-peer voice 8011 pots
destination-pattern 8012...
preference 1
port 0/0/0:23
translation-profile outgoing 801PSTN
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IP WAN
PSTN
voice translation-rule 2
rule 1 /^8022/ /2/
voice translation-profile intersite-in
translate called 2
dial-peer voice 8011 voip
destination-pattern 8012...
session-target ipv4:10.10.0.1
translation-profile incoming intersite-in
ANI
DNIS
80120018012001
20018022001
OutgoingIncoming
10.10.0.1Phone 2-1
2001Phone 2-1
2001
San Jose Austin
R3
Inbound Site-Code Dialing Example
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Configuring TEHO
1. Define the VoIP outbound digit manipulation for TEHO.
2. Define the outbound VoIP dial peer for TEHO.
3. Define the outbound POTS dial peer for TEHO.
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TEHO Scenario
IP WAN
Phone1-12001
Phone1-22002
Phone2-12001
Phone2-22002
San Jose Austin
R1 R3
4085550100
Use the WAN linkfor calls to the SanJose PSTN.
If the WAN fails, usethe Austin PSTN.
192.168.1.1
DID: 408555XXXX DID: 512555XXXX
PSTN
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R3
voice translation-rule 10
rule 1 /^2/ /15125552/
voice translation-profile SJC-TEHO-OUT
translate calling 10
Step 1: Define VoIP Outbound DigitManipulation for TEHO
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R3
dial-peer voice 914081 voip
destination-pattern 91408.......
session-target ipv4:192.168.1.1
translation-profile outgoing SJC-TEHO-OUT
Step 2: Define Outbound VoIP TEHODial Peer
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Step 3: Define Outbound POTS TEHODial Peer
R3
dial-peer voice 914083 pots
destination-pattern 91408.......
prefix 1408
preference 1
port 0/0/0:23
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Summary
The call routing logic on Cisco IOS routers, using the H.323 orSIP protocols, relies on the dial peer construct.
Routers must match the correct inbound and outbound dial peersto successfully complete a call.
Dial peers in a hunt group are selected according to criteria suchas longest match, explicit preference, and random selection.
Best practices include a default POTS dial peer and redundantCisco Unified Communications Manager servers.
When remote sites are involved, different path selectionstrategies are required, including site-code dialing, toll bypass,and TEHO.
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Site-code dialing uses the concept of prefixing a site code in frontof the actual extension and can be combined with toll bypass toroute calls over a WAN link instead of a PSTN connection.
TEHO extends the concept of toll bypass by routing calls over the
WAN to the closest PSTN breakout to avoid costly long distanceand international phone charges.
Site-code configuration requires that each site be assigned aunique site code.
TEHO configuration requires that all calls be routed over the
WAN unless it is down or has been oversubscribed and blockedby CAC.
Summary (Cont.)
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