Blocking Commonly Exploited Area Codes

When blocking commonly exploited area codes, create a unique route pattern for each area code that you want to block. You can create different restriction levels; for example, general employees are not allowed to call these numbers, but executives and managers are allowed to. Use different route filters, partitions, and calling search spaces to generate restriction levels. As a general recommendation to prevent toll fraud, you should block as many numbers as possible. For the example shown in Figure 22-4, all calls to the Bahamas are blocked. For each number that you want to block, create a route pattern that explicitly blocks the number. Often, the decision as to whether a number should be blocked or allowed depends on company policies or simply on whether it is necessary to call the number.

Figure 22-4. Restricting Specific Area Codes

Table 22-1 shows some of the most commonly exploited area codes that you might want to block. It is not an exhaustive list, and some of these area codes might not apply to your organization.

Table 22-1. Commonly Exploited North American Area Codes

Country

Area Code

Blocked Cisco CallManager Pattern

Anguilla

264

9.1264xxxxxxx

Antigua/ Barbuda

268

9.1268xxxxxxx

Bahamas

242

9.1242xxxxxxx

Barbados

246

9.1246xxxxxxx

Bermuda

441

9.1441xxxxxxx

British Virgin Islands

284

9.1284xxxxxxx

Cayman Islands

345

9.1345xxxxxxx

Dominica

767

9.1767xxxxxxx

Dominican Republic

809

9.1809xxxxxxx

Grenada

473

9.1473xxxxxxx

Jamaica

876

9.1876xxxxxxx

Montserrat

664

9.1664xxxxxxx

Puerto Rico

787

9.1787xxxxxxx

St. Kitts & Nevis

869

9.1869xxxxxxx

St. Lucia

758

9.1758xxxxxxx

St. Vincent & the Grenadines

784

9.1784xxxxxxx

Toll Charge

900

976

9.1900xxxxxxx

9.1976xxxxxxx

Trinidad & Tobago

868

9.1868xxxxxxx

Turks & Caicos Islands

649

9.1649xxxxxxx

U.S. Virgin Islands

340

9.1242xxxxxxx

In the worldwide country code numbering scheme, several countries do not use their own country codes.

These numbers have the same format as the NANP[access code] [area code] [number] (for example, 9.142xxxxxxx)but a call to one of these destinations results in an international toll charge.

Administrators should make sure that all of the devices in the IP telephony network can reach only the destinations that they should be able to reach. For example, a lobby phone should not be able to call international numbers. In situations in which individuals in your organization have legitimate business in one of these countries, the recommendation is to explicitly configure route patterns that will match those businesses, while still blocking the area code as a whole.

Part I: Cisco CallManager Fundamentals

Introduction to Cisco Unified Communications and Cisco Unified CallManager

Cisco Unified CallManager Clustering and Deployment Options

Cisco Unified CallManager Installation and Upgrades

Part II: IPT Devices and Users

Cisco IP Phones and Other User Devices

Configuring Cisco Unified CallManager to Support IP Phones

Cisco IP Telephony Users

Cisco Bulk Administration Tool

Part III: IPT Network Integration and Route Plan

Cisco Catalyst Switches

Configuring Cisco Gateways and Trunks

Cisco Unified CallManager Route Plan Basics

Cisco Unified CallManager Advanced Route Plans

Configuring Hunt Groups and Call Coverage

Implementing Telephony Call Restrictions and Control

Implementing Multiple-Site Deployments

Part IV: VoIP Features

Media Resources

Configuring User Features, Part 1

Configuring User Features, Part 2

Configuring Cisco Unified CallManager Attendant Console

Configuring Cisco IP Manager Assistant

Part V: IPT Security

Securing the Windows Operating System

Securing Cisco Unified CallManager Administration

Preventing Toll Fraud

Hardening the IP Phone

Understanding Cryptographic Fundamentals

Understanding the Public Key Infrastructure

Understanding Cisco IP Telephony Authentication and Encryption Fundamentals

Configuring Cisco IP Telephony Authentication and Encryption

Part VI: IP Video

Introducing IP Video Telephony

Configuring Cisco VT Advantage

Part VII: IPT Management

Introducing Database Tools and Cisco Unified CallManager Serviceability

Monitoring Performance

Configuring Alarms and Traces

Configuring CAR

Using Additional Management and Monitoring Tools

Part VIII: Appendix

Appendix A. Answers to Review Questions

Index



Authorized Self-Study Guide Cisco IP Telephony (CIPT)
Cisco IP Telephony (CIPT) (Authorized Self-Study) (2nd Edition)
ISBN: 158705261X
EAN: 2147483647
Year: 2004
Pages: 329

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