$phoneTypes = CRM_Core_PseudoConstant::get('CRM_Core_DAO_Phone', 'phone_type_id');
$phoneTypeLabel = CRM_Core_PseudoConstant::getLabel('CRM_Core_DAO_Phone', $phoneType);
$this->add('select', 'phone_type_id', ts('Phone Type'), $phoneTypes);This code will add a select field to a CRM_Form which allows users to select a phone type from the available options. The CRM_Core_PseudoConstant phoneType is a part of the CiviCRM package library.