How To Install Voice Over IP

Fully global, end-to-end voice over IP (VoIP) is not yet practical for all organizations. But intra-office VoIP hardware can be deployed in data routers and managed with the same tools used to maintain the data routers. With VoIP, data and voice are married on a single wire. The result: network complexity is reduced, and accountability is consolidated.

Also, with VoIP it is the phone itself, not the physical wire (as with traditional PBX systems) that establishes the identity and phone number of the caller. It does this via its MAC address, a unique, distingushing serial number burned into a network adapter. This can be an important distinction and a key feature for fluid office environments, especially where PCs are used as "soft phones." The extension number remains associated with the hardware, not the location, so as people move from cubicle to office to conference room, they remain reachable at the same number, transparent to intra-office callers as well as the outside world.

Especially for green-field sites and existing offices that are undergoing a massive IT overhaul, VoIP offers single-wire simplicity and a one-stop management solution for all voice and data traffic.

Leading telecom and networking manufacturers, including Nortel, Siemens, and Cisco, are eagerly introducing business-class VoIP across their product offerings. So you don't have to look far to find an OEM willing and able to help you supply your clients with a unified voice/data environment. We will illustrate our recipe with Cisco gear, though you can of course use equivalent products from other vendors.

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This recipe describes a green-field implementation of a small-ofice VoIP network. At its completion you will have an operational combination voice and data router, as well as several VoIP phones configured for office workers. There's no need for dedicated racks and cable nests just for voice service.

Ingredients

From Start To Dial Tone

Now that we have our components assembled, let's start building the VoIP network. Here are 11 steps to VoIP success:

1. Before any internal work is done, you or the customer must arrange an outside connection with the customer's telelcom-services provider. Fortunately, nothing is different for the customer or the provider at this step. As far as the telco is concerned, a VoIP network looks exactly like a traditional PBX. All you have to do is find out the type of connection (T1, FXO, etc.) and order the proper network module to suit.

2. Assemble the VoIP gear. All the parts listed above, including the CallManager Express software, may be purchased preinstalled from Cisco. Our contacts at Cisco dubbed this configuration the CISCO3745-V-CCME-A bundle. All components will come installed with generic setup steps already performed. Additional modules, such as inline Ethernet power, may require field installation.

3. Connect the FXO/T1 network module to the central office trunk provided.

4. Using your Cat 5 cabling, deploy the IP phones. Remember that each phone has a two-port switch, so most workspaces will only need a single line run from router or workgroup switch to the desktop. Link each phone with the router, then connect the desktops to the phone's other 10/100BaseT port.

5. Turn on the central timekeeper. The VoIP network relies on a central timekeeper. Cisco ships routers with Network Time Protocol (NTP) service disabled, but it should be turned on for smooth operation and easier configuration of new phones.

Here's the command sequence to set the clock and get NTP running:

6. CCME can automatically discover and configure phones on the network. Launch telephony-service setup from an IOS CLI (command-line interface) prompt. This invokes a text-based Setup Tool Wizard. Before running the Wizard, be prepared to answer the following questions:

Here's the CLI summary for this step:

7. Configure a basic, fully consultative transfer system. Most offices will want some form of call transfer. Both blind (immediate connection) and consultative transfers are supported. With consultative transfers, two internal users can confer about the transfer before the caller is reconnected.

To configure a basic, fully consultative transfer system, enter the following sequence in the CLI:

The transfer-pattern command may be used before the exit to include a range of outside dial numbers as valid transfers. Without it, only extensions within the VoIP network are valid transfer destinations.

8. Save clients expense and embarrassment by excluding all 1-900 number calls using a simple CLI sequence:

9. Set the CLI aside except for elaborate configuration problems. CallManager Express (CCME) relies heavily on Web-based GUI configuration. If the router was purchased new in step 1, its HTTP server is disabled by default. Coordinate with the system administrator to enable HTTP access for admin accounts. The CLI command sequence will be of the form:

Next, activate the GUI itself. The command sequence is of the form:

The CCME GUI may then be opened in a browser window, pointing to http://192.168.20.0/ccme.html. Substitute the IP address of the router as appropriate.

10. Use the CCME GUI to create any additional, necessary administrator accounts. Also use it to create user accounts for each phone, so employees are authorized to configure voicemail and perform other basic tasks.

11. In the CCME GUI, verify that users have their desired extensions. The phones were auto-discovered and numbered sequentially with the setup wizard, but some clients may require vanity extensions for certain users. The Configure/Extensions screen allows extensions to be created, deleted, and reassigned to a different MAC address. The Change Phone screen also allows the administrator to set up certain personal features for the user, such as pre-populating speed dials.

At this point, you should have a happy, healthy IP telephony environment, with dial-tone to the outside world and all the convenience of a one-line, one-box administration. The CCME GUI is loaded with complex features, and even more esoteric configurations are possible through the use of the telephony-service series of commands available from the CLI. It will make that wheezing AT&T Merlin setup being replaced look positively Stone Age.

JASON COMPTON is a technology writer who has covered topics ranging from 8-bit entertainment to supercomputing for more than a decade.