Digitmaps are templates that are constructed based on the dialing plan to match different sequences of digits that users dial so that the device can send out the dialed digits to the respective SIP proxy/server in a timely manner. For the BuddyTalk product Digitmap rules and syntax, please see BuddyTalk Dialing Plan and Digitmaps.  Below is a Digitmap constructed for a typical U.S. dialing plan:

[2-9]xxxxxx|1[2-9]xxxxxxxxx|011x.T|[0-9*].#|*xx

When dialing from within an enterprise IP-PBX encvronment, it is typical that one or multiple prefix numbers are added to the callee numbers for external calls, and numbers with a smaller number of digits are used for internal extensions.  For example, a system reserves 4-digit numbers with the leading digit between 2 and 7 as internal extension numbers, the digit 9 is used as a prefix for external calls, and dialing 0 is to call the local operator/receptionist. The Digitmap for such a dialing plan is given below

0|[2-7]xxx|9[2-9]xxxxxx|91[2-9]xxxxxxxxx|9011x.T|[0-9*].#|*xx

The BuddyTalk products offer multiple convenient call control mechanisms, some are natural to dial with the prefix (e.g., POTS calling), and some are more natural not to have a prefix (e.g., voice commands based calling). To take into account these different dialing patterns, the above Digitmap can be augmented to handle dialings with or without prefix:

0.T|[2-7]xxx|9[2-9]xxxxxx|[2-9]xxxxxx.T|91[2-9]xxxxxxxxx|1[2-9]xxxxxxxxx|9011x.T|011x.T|+x.T|[0-9*].#|*xx

While the augmented Digitmap takes care of gathering and sending out the user dialed digits in a timely mannter, the dialed numbers may still be missing with the required prefixes, thus, insufficient for IP-PBXs.  This is where the Digit Replacement Rules can be used.  A properly constructed Digit Replacement scheme replaces or adds to the numbers matched by the Digitmap with the desired numbers or digits to fit the dialing plan requirements.  The Digit Replacement Rules for the dialing plan and the augmented Digitmap is given below:

 /|/|/|/9|/|/9|/|/9|+/9011|/|/

Please check Dialing Plans, Digitmaps, and Digit Replacement Rules for detail.  Please note that 

• The Digit Replacement Rules are applied to the Voice Commands dialing, the TC dialing, and the Mobile App dialing, but not used in the POTS phone dialing.  Therefore, when using POTS phone to make calls, prefixes is required for external calls. 
• The Digitmaps are applied to the POTS phone dialing in a digit-by-digit matching manner as the user dials the number, and the first (shortest) match will trigger the digits to be sent out.  On the other end, the Digitmap process chooses the longest match when used to choose the corresponding Digit Replacement rules to be applied to the Voice Commands dialing, the TC dialing, and the Mobile App dialing.
• The Contacts used in the voice commands may not be identical to the Contacts used when calling through the Tablet Controller or the Mobile App, as the Contacts used in the voice command calling are from the Alexa App, while the Contacts used in the Tablet Controller and Mobile App calling are from the devices’ Contacts respectively.