4g is just 3g with a wider reception thats about it.
With VoIP, you use an IP network, through an ADSL or other Internet connection, to make/receive phone calls to/from PSTN landline networks. You can even talk to people with a landline phone number through your computer, for example using SkypeIn and SkypeOut
http://voip.about.com/od/voipbasics/f/IPToPSTN.htm
its a big reason why i think americas internet infrastructure should be heavily government subsidized (paid by taxpayers). make us all pay for it, but give us all a free decent speed option.
that way it would insure that net neutrality is upheld, and it would allow VOIP to become a sole standard. POTS could be completely eliminated if everyone had an internet connection, even if some people used their connection just for phone.
some argue that POTS is a safe backup for basic communication, but i think thats what cell phones and am/fm radio is for. POTS is just redundant costly crap in this day and age.
The PSTN is not and cannot be "VoIP". The two are not compatible.
VoIP can "on-ramp" to the PSTN. This is how VoIP service providers provide connectivity to existing infrastructure. However, the VoIP network itself is a completely different network.
Now, if you're asking "when will the PSTN start using packet switched (as opposed to circuit switched) voice throughout" then the answer is "it already is. kind of". Much of the long-distance networks have been redesigned to be packet-switched, because it's cheaper.
The other question is "when will we ditch copper circuits for voice". This, also, has been well in the works. AT&T Uverse voice is packet-based. They simply use the copper as a transport medium for the VDSL signal. This is similar to Comcast's voice. Comcast's voice is packet voice over the cable.
We will never get away from physical line connectivity. Wireless just isn't reliable enough. However, we are starting to get to the point where the VoIP infrastructure is expanding at a rate faster than the PSTN infrastructure. This is a good thing.
However, there are many efforts that will thwart the adoption of a purely packet-switched voice network. Namely, net neutrality. Also, the clinging to fax machines makes it extremely difficult to get away from traditional TDM copper.
What I have been waiting for someone to point out is ...
that VoIP would be redundant on POTS.
AND
VoIP is the competition to POTS.
AND
POTS does not have the bandwidth.
What I meant to say is when VoIP will take over PSTN as the main standard for telephony.
its a big reason why i think americas internet infrastructure should be heavily government subsidized (paid by taxpayers). make us all pay for it, but give us all a free decent speed option.
that way it would insure that net neutrality is upheld, and it would allow VOIP to become a sole standard. POTS could be completely eliminated if everyone had an internet connection, even if some people used their connection just for phone.
some argue that POTS is a safe backup for basic communication, but i think thats what cell phones and am/fm radio is for. POTS is just redundant costly crap in this day and age.