Face-Off: Analog-to-Digital vs VoIP
The strongest argument in favor of VoIP is that it is cheap, and thus poses a threat to traditional circuit switching systems employed by the (cellular) mobile service providers as well as the age old Public Switching Telephone Network (PSTN). The rate for voice calls has traditionally been directly proportional to the distance to where the calls are made, with international calls being too expensive even today.
Comparing Internet telephone under the same umbrella, it costs almost nothing to make an international call using internet telephony. VoIP service internet phone systems can integrate with added services available on the internet,like video conference, message or computer file exchange, conversation conferencing. It can also make use of a computer's address book, including any policy details concerning whether others like friends or co-workers can be found online as well as your customers.
Voice over internet protocol can perform tasks that might be harder to attain using traditional systems. Incoming telephone calls could be instantly routed to your VoIP phone, no matter where you are. Take your voice over internet protocol phone along with you on holidays, and wherever a connection to the web is attained, you are able to receive calls.
There are fair share of disadvantages for VoIP service as well. The traditional switching system, being a closed system, is very secure against internet telephone. The Quality of Service (QoS) aspect of internet telephony is still under consideration. Another drawback may be the difficulty in delivering faxes because of software as well as networking constraints in the majority of home systems. Attempts are going ahead to solve this by determining another IP solution that delivering Fax via IP, called the T.38 protocol. Other possible means to fix the drawback would be to treat fax systems like message switching systems which don't require live data transmission - for example delivering a fax as email attachments or remote printout eventually systems may substantially reduce incoming printable fax data or image.
It is witnessed till date that although VoIP service has gained popularity and more and more people are interested in having VoIP communications, the revenues of the carriers have still not suffered financially. The defense by carriers for going against VoIP has been that people want, quality, reliability and ease of use and VoIP does not provide any of that. But the main reason for them is the expensive switching system that the carriers already have.