Preparing for VOIP

Implementing a Voice Over IP system can stress networks in new and different ways. 

When planning an upgrade to VOIP, take a look at this checklist to help ascertain whether your network is ready for VOIP.

• Cabling:

Is the Ethernet segment in question built on Category 5 or better cable with UT/RJ45 connections?

Do they terminate centrally, near the switches?

• Power:

Can the existing switches provide PoE (Power over Ethernet) or will power injectors be needed?

If so, is there sufficient available rack space?

• DNS:

Are there DNS servers accessible on this network segment?

• VLAN:

Can all the existing switches provide a VLAN?

• IP Addressing:

Does the LAN segment have a DHCP server?

• Address Space:

Does the DHCP server have sufficient address space to support the number of IP phones?

• Topography:

Do you have an up to date network diagram, showing addresses and locations?

• Documentation:

Ensure that accurate documentation exists for routing policies and VLAN configuration

• Resilience:

Are all necessary devices provided with backup power by UPS or generator?

• Switching:

Do all switches and routers support IP precedence and/or ToS?

• Network Performance:

Is the nominal packet loss on the Ethernet segment sufficiently low? Aim for less than 1%.
 

Once these basics are taken care of, identify server device requirements. For example:

- PBX / Switch

- Voicemail Server

- PSTN / TDM Gateway

- Analogue Endpoint Gateway

- TFTP Server (if needed)

- LDAP or other Directory Server

- DNS Server

- DHCP Server

- Firewall, NAT Device, Gateway Router

- Default Router

With this information to hand, you will be better placed to judge the readiness of your network for a VOIP implementation. Additionally, this data will be of significant help when budgeting for any necessary upgrades, and will mean that you have on hand the majority of the information that a supplier or installer might need prior to a site survey.

VOIP can offer enormous advantages, but the rollouts that work best are the ones that are planned well. Do your homework up front, and you will minimize the pain down the line!