From ContactWorld version 2.12 in Salesforce, if enabled for your account, you can configure ContactWorld to dynamically select a callback number based on the value in a field in the record that contains the dialed number. This method does not require Apex code as the code is provided in the managed package.
For example, you might want ContactWorld to present one callback number when your agents click to dial contacts in the finance department and another for contacts in the legal department. ContactWorld will present the default callback number when dialing contacts in any other department.
Before you can configure this feature, you or your Salesforce administrator must perform the following tasks. The administrator needs to perform these tasks one time only.
- Specify which class ContactWorld must use to select the callback number. You specify the class in the custom settings data for your org, profile or user. Type NVMContactWorld.SelectPresentedCLIDByField in the Callback Number Selector Class field. For more information about configuring custom setttings, see Configuring custom settings for optional ContactWorld features in Salesforce.
Configure supervisor and agent permissions to the Field-Based Callback Number Mapping custom object:
Object Read Create Edit Delete Supervisor 
Agent 
Configure supervisor and agent permissions to the fields on the Field-Based Callback Number Mapping custom object:
User type/profile Read Edit Supervisor Agent - Configure sharing settings for the Field-Based Callback Number Mapping object if you want to restrict the access different profiles have to other profiles' records. For information about sharing settings, see Salesforce help.
- Set the Field-Based Callback Number Mapping object tab to Default On for supervisors.
When your administrator has enabled the feature, you can create mappings. These map the value in specific fields to specific callback numbers. To create a new mapping, perform the following steps:
- Go to the Field-Based Callback Number Mapping object tab, click Field-Based Callback Number Mappings in the View list and click Go!. Any existing mappings appear.
- Click New Field-Based Callback Number Mapping. A new Field-Based Callback Number Mapping record appears.
Provide the following information:
Field Description Example Mapping Name A name for this mapping. Callback for VIP accounts Object The type of Salesforce object that the agent has clicked to dial from. The object type contains the field which the callback number is based on. Account Field The field on the Salesforce record that contains the value which the callback number is based on.
You must specify the full API name of the field, including the package name if relevant. For example, NVMContactWorld__CustomerPriority__c.Account_type Value The value that the field must contain to return the number in the Presented Callback Number field. The Value field can contain any alphanumeric value or you can leave the field empty. If you do not provide a value in the Value field, if the field on the record is also empty, ContactWorld presents the number in the Presented Callback Number field. VIP Presented Callback Number The callback number that ContactWorld will display when the field's value matches the value in the Value field.
You can only use callback numbers that are configured for your account. If you use a number that is not configured for your account, ContactWorld cannot make outbound calls that use this prefix mapping record. The error message "The call to number dialed number could not be made as the presented CLID presented callback number is restricted or is not available on your account." appears in your agent's ContactPad.
02072068888 
- Click Save.
Now when an agent clicks to dial a phone number in an account record with a value of 'VIP' in the Account_type field, ContactWorld uses 0207206888 as the callback number.
In the absence of any other mappings, when an agent clicks to dial a phone number from an account record with any other value in the Account_type field or from any other object, ContactWorld uses the default callback number. This default callback number can be for the account or for the agent. Which callback number ContactWorld uses depends on the current configuration. For more information about callback numbers, see Callback numbers.