Choosing to Implement IP Telephony
IP telephony sounds great, right? Shouldn’t every organization have implemented
it by now? Well, first of all, you should keep in mind that voice traffic and regular
IP data traffic are two completely different solutions. Regular Transmission
Control Protocol/IP (TCP/IP) data traffic is very resilient. It can be forgiving of
slow wide area network (WAN) links, lost packets, and the reception of packets
out of sequence. In fact,TCP/IP operates in just that way, taking data and segmenting
it into several packets and transmitting the data via the best possible path.
It is not concerned with the order in which the data is received, or the path it
takes to get there, because the end device is responsible for the reassembly and
resegmentation of the data.Voice traffic, on the other hand, is not so forgiving, nor
as resilient. Even though the voice traffic is being converted to IP packets, it is still
voice traffic. IP telephony depends on packets being received in the same order in
which they were sent; if a packet is lost, then it should remain lost, as retransmitting
the packet would only confuse the person on the receiving end of the call. In
order to accomplish this, you must incorporate several new features on your
routers and switches, such as Queuing and Real-Time Transport Protocol (RTP).
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In fact, in order to make IP telephony a reality, your infrastructure is going to
need quite a few enhancements.There are several components that must be
added to your infrastructure.These components include, but are not limited to,
specialized router interfaces, specialized local area network (LAN) switch modules
and interfaces, IP telephone handsets, Cisco CallManager servers, and Cisco
Unity Mail, as well as other unified messaging solutions. In addition to the
required hardware, there are several applications that will also help you to realize
the benefits of IP telephony. Applications such as Cisco’s WebAttendant,
AutoAttendant, and Personal Assistant, as well as third-party software should also
be incorporated into your IP telephony solution.