A2Billing Customisation/50 SpeedDial to DirectDial

General information for the business: Enabling 50 SpeedDial to Direct Dial Feature in A2Billing
Database management system (DBMS): MySQL
Description of requirements/functionality: It i called Speed Dial, Called Direct Dial i A2Billing and it works like this (bellow), customisation I need is that A2Billing has 10 DIDs while I need 50 DIDs and an option in the customer web-interface to manage (add/delete/amend DIDs to destination phone numbers) this DIDs.

http://www.asterisk2billing.org/add-ons/access-number-to-speed-dial/

There are 50 DID have been added to asterisk/a2billing along with few other DIDs for local Access Numbers. Now these 50 DIDs will be allocated to the entire customers of the site and from every customers account they will be able to add/delete/change DID to destination so that they dont have dial the access numbers instead just dial the assigned DID for a particular destination.

and these 50 DIDs will be used for the entire customer base and evey customer will be able to use 50 DID as the combination in each case is unique.

Hope that helps.
CMS and Admin requirements: There has to be a module in the A2Billing Customer Web Interface so that they can manage this DIDs.
Specific technologies required: PHP
Extra notes: