Well, we need to be careful not to confuse things here. IP phones and digital phones are not really the same thing. Digital phones have improved capabilities over analog phones, but are not necessarily IP-enabled. Generally, digital phones are well designed and support PBX systems quite nicely. They tend to be sturdy and reliable, but also rather expensive. For the most part, though, they are purpose-built and can only support TDM-based telephony. As a company's communications needs evolve beyond this, digital phones become rather one-dimensional.
IP phones, on the other hand, are built to support IP first and telephony second. The concept is quite different from digital phones, which are only designed to support one mode. When businesses start to embrace the richer world of IP communications, the benefits of IP phones become more evident. With IP phones, they now have a bridge to converged services, which incorporate voice into data and video applications. Basic IP phones enable this to some degree, while more advanced IP phones are really multimedia endpoints that bring all these capabilities together with a single interface.
In terms of limitations, basic IP phones can't do much beyond voice, so if that's not enough, you'll need a more advanced model. These phones have a larger graphical interface with browser support and often have touch screen features. Voice is just one feature of many, but it should be noted that with IP, these phones often support wideband codecs, which means HD voice and a more engaging user experience.
Initially, IP phones were more expensive than analog or digital phones, and this really inhibited adoption. Over time, though, the advantages have become better understood, and as demand increased, prices declined, making them even more affordable. Today, IP phones have comparable price parity with digital phones, and this factor is no longer a major obstacle to buying.
This was first published in April 2010