There are many IP-based phones on the market but they’re not all the same. What communication system you are connecting to will drive your decision. Selecting the right phone for your environment must also deal with compatibility and interoperability. It’s easy to make a mistake.
IP Phone Defined
An IP phone uses voice over IP technologies for placing calls connected to an IP network. This could be the Internet or a local area network. This is an alternative to connecting to the public switched telephone network, the PSTN. The primary difference among the voice over IP phones is the signaling protocol that is used. The session initiation protocol known as SIP is a standard that many providers and vendors support. But there also IP phones on the market that support the standard H. 323, Cisco’s skinny protocol, and other proprietary protocols.
IP vs. SIP Phone
IP phones and SIP phones both use voice over IP technology. IP phones can offer standard and nonstandard signaling protocols but may not be compatible with services such as Salesforce, Dropbox and Microsoft office. SIP phones use the session initiation protocol exclusively. SIP phones are commonly interoperable and compatible with many IP PBXs and unified communications service providers.
Interoperability
Choosing a phone to connect to an IP network is a matter of interoperability and compatibility. When you look at the phone vendor, consider what alliance and interoperability partners they have listed. Internet telephony service providers can be a partner as well as a unified communications as a service provider. There are also legacy carriers that support IP phones. Two things that are also of concern are security and encryption used by the IP phones. You also need to consider how to manage the remote phones especially the use of the Real Time Control Protocol (RTCP) performance measuring standard.
PoE for IP Phones
VoIP phones can be powered locally. However it’s most common that you use power over Ethernet (PoE) to power the phone. The LAN provides the power source. Some of the ports on your existing LAN switch may not support power over Ethernet at all. The power consumed by the phones will also vary. An important point is backing up the power for the PoE phones. You need to provide battery or generator support otherwise when the power goes out, you phones go out.
An alternative connection approach is called long-range POE which can extend the distance beyond 300 feet to 1200 feet for your IP phones. Long-range POE can operate over legacy telephone cable using a single pair of wires.
IP Phone Configurations
There are three common configurations for connecting IP phones to LAN switch. The first one is where the phone can connect to the PC then to the LAN. But this requires dual port access on the PC, which it is not preferred. The PC provides the PoE to the IP phone.
The second is connecting the phone directly to the LAN switch in parallel with the PC. This is the best approach. It can help you designate a separate LAN so that you don’t have data interference and you can increase security.
The third phone configuration is a phone with dual ports, one to connect to the PC and one port connected to the LAN switch. Ensure that the phone does restrict the PC speed.
Selection Criteria
If you’re connecting to an IP PBX or unified communications provider, they will specify what phones are compatible with their IP PBX or network. You need to know who’s going to be using these IP phones. For example if there are a lot of incoming calls, do you need multiple line appearances? Is it going to be heavily used, then you need a rugged and reliable device.
You probably will use power over Ethernet. You have to check with your IT department make sure that there is enough PoE ports on the LAN switches. Lastly, what protocols and codecs are supported by the service provider or PBX vendor?
Feature Selection
You need to add the required features and functionality to the selection criteria list. If you want cordless phones, do they support the DECT 6.0 standard? Do you need a screen, if so how big, color, and touch sensitive? Do you want programmable keys for special functions? If this is for help desks or contact centers, are they operating hands-free? In the contact center help desk, do you want a headset that can be attached to the phone? What features do you want in the conference units, extensions, cordless, and sound control?
Source: TelecomReseller
