Digit Manipulation on Cisco IOS

With digit manipulation on IOS, keep a few things in mind:
1.  / -- /    - It always starts with / and ends with /
2. Anything within parenthesis would be kept.
 characters are keep are like (a\)
 characters to ignore are like b\
 \1 copy the first set into the replacement number, \2 copy the second set into the replacement number, etc 
 
3. The following represents the digits/characters:
 . : Any single digit
 0 to 9,*,# : Any specific character
 [0-9] : Any range or sequence of characters
 * : Modifier—match none or more occurrences
 + : Modifier—match one or more occurrences
 ? : Modifier—match none or one occurrence

Look at the following examples. This should clarify:

Examples:

Example 1:
voice translation-rule 1
 rule 1 /123/ /456/

Will match and modify 123 anywhere in the pattern:

router#test voice translation-rule 1 123
Matched with rule 1
Original number: 123    Translated number: 456

router#test voice translation-rule 1 1234
Matched with rule 1
Original number: 1234   Translated number: 4564

router#test voice translation-rule 1 6123
Matched with rule 1
Original number: 6123   Translated number: 6456
router#test voice translation-rule 1 6123123
Matched with rule 1
Original number: 6123123        Translated number: 6456123

Example 2:
voice translation-rule 1
 rule 1 /^123/ /456/  
 
Will match only if the pattern start with 123 because carrot '^' is the starting character

router#test voice translation-rule 1 123 
Matched with rule 1
Original number: 123    Translated number: 456

router#test voice translation-rule 1 1234
Matched with rule 1
Original number: 1234   Translated number: 4564

router#test voice translation-rule 1 6123
6123 Didn't match with any of rules 

Example 3: 
voice translation-rule 1
 rule 1 /^123$/ /456/

Will only match if the pattern starts if its 123 exacly. Nothing after, nothing before.
 
router#test voice translation-rule 1 123 
Matched with rule 1
Original number: 123    Translated number: 456

router#test voice translation-rule 1 1234
1234 Didn't match with any of rules

router#test voice translation-rule 1 6123
6123 Didn't match with any of rules


Example 4:

voice translation-rule 1
 rule 1 /^40.../ /6666000/
 
Will match pattern starting with 40 and any 3 digits afterwards

router#test voice translation-rule 1 40123
Matched with rule 1
Original number: 40123    Translated number: 6666000

Example 5:

voice translation-rule 2
 rule 1 /.*/ /5554000/
 
Will replace any pattern with 555400

router#test voice translation-rule 2 123
Matched with rule 1
Original number: 123    Translated number: 5554000

router#test voice translation-rule 2 86573
Matched with rule 1
Original number: 86573  Translated number: 5554000

router#test voice translation-rule 2 ""
Matched with rule 1
Original number:   Translated number: 5554000

Example 6:

voice translation-rule 1
 rule 1 /^\(12\)3\(45\)$/ /6\1\2/

Set 1: 12
Set 2: 45
Ignore: 3

router#test voice translation-rule 1 12345
Matched with rule 1
Original number: 12345        Translated number: 61245

Example 7:

voice translation-rule 10
 rule 1 /\(32..\)$/ /416555\1/
 
Will replace 32xx to 41655532xx (used for outbound caller ID)

router#test voice translation-rule 10 3200
Matched with rule 10
Original number: 3200  Translated number: 4165553200

Example 8:

voice translation-rule 10
 rule 1 /^416555\(32..\)$/ /\1/
 
Will replace 4165553211 to 3211 (used for inbound caller ID)

router#test voice translation-rule 10 4165553211
Matched with rule 10
Original number: 4165553211  Translated number: 3211

Example 9:

voice translation-rule 7
 rule 1 /^4/ /904/ type national national
 rule 2 /^4/ /9004/ type international international
 
If number starts with 4 and type is National, it would be prefixed 90 and type will remain National
If number starts with 4 and type is International, it would be prefixed 900 and type remain International
 
router#test voice translation-rule 7 493456567 type national
Matched with rule 1
Original number: 493456567      Translated number: 90493456567
Original number type: national  Translated number type: national
Original number plan: none      Translated number plan: none
    
router#test voice translation-rule 7 493456567 type international
Matched with rule 2
Original number: 493456567              Translated number: 900493456567
Original number type: international     Translated number type: international
Original number plan: none              Translated number plan: none
 
Example 10:

voice translation-rule 8 
 rule 1 /^2\(...$\)/ /01779345\1/ type unknown national plan unknown isdn
 
This rule matches any four-digit number that starts with "2". The rule removes the "2", adds the number "01779345" as a prefix, and sets the plan to "isdn" and the type to "national".
 
router#test voice translation-rule 8 2001 type unknown plan unknown 
Matched with rule 1
Original number: 2001   Translated number: 01779345001
Original number type: unknown   Translated number type: national
Original number plan: unknown   Translated number plan: isdn 
 

 
POTS Dial-Peers
---------------

dial-peer 911 pots
 destination-pattern 911$ !Anything that is explicitly matched on POTS dial-peer is removed. This isn't true for VOIP. VOIP Dial-peer doesn't remove anything thats explicity matched.
 no digit strip <OR> prefix 911 <OR> forward-digits 3
 port 0/0/0:23 
 
dial-peer 9 pots
 destination-pattern 9[2-9]XX[2-9]XXXXXX$
 port 0/0/0:23
 ! no need for any prefix or any forward digits as only number explicitly matched is 9 which we want removed as its our PSTN code.
 
dial-peer 91 pots
 destination-pattern  91[2-9]XX[2-9]XXXXXX$
 prefix 1 <OR> forward-digits 11 ! 1 is being explicitly matched and we want it to go out as its our long distance code used by the PSTN.
 port 0/0/0:23
 
dial-peer 9011 pots
 destination-pattern 9011T ! no need for #. It would be automatically matched because of the next dial-peer.
 prefix 011 ! can't use forward-digits as we don't know the extension length that would be dialed. 
 port 0/0/0:23
 
dial-peer terminator # ! Its a default command and any call with # is already a terminator for interdigit timeout, unless its changed by someone.

Note: On CUCM, in Service Parameters "Strip # Sign from Called Party Number" is "True" by Default - Meaning it would remove # as the trailing number.


dial-peer 1 pots
 incoming called-number . ! will match incoming calls
 
dial-peer 2 voip
 destination-pattern 2...$
 session target ipv4:10.1.1.2 ! CUCM IP
 dtmf-relay h245-signal
 
dial-peer 3 voip
 incoming called-number .


Overlap Sending <-- SCCP works this way - one digit at a time.
En-Bloc <-- CUCM works this way.

A good document which I consulted when working on this post:
​http://www.cisco.com/c/en/us/support/docs/voice/call-routing-dial-plans/61083-voice-transla-rules.html