X-Received: by 2002:a37:a915:: with SMTP id s21mr6475755qke.436.1585457328326; Sat, 28 Mar 2020 21:48:48 -0700 (PDT) X-Received: by 2002:a05:620a:49d:: with SMTP id 29mr6783799qkr.206.1585457327977; Sat, 28 Mar 2020 21:48:47 -0700 (PDT) Path: csiph.com!xmission!news.snarked.org!border2.nntp.dca1.giganews.com!nntp.giganews.com!news-out.google.com!nntp.google.com!postnews.google.com!google-groups.googlegroups.com!not-for-mail Newsgroups: comp.dcom.telecom.tech Date: Sat, 28 Mar 2020 21:48:47 -0700 (PDT) Complaints-To: groups-abuse@google.com Injection-Info: google-groups.googlegroups.com; posting-host=75.167.99.73; posting-account=Sc65mwoAAAAb9LjVPpVyBjKP4GHo7Ozs NNTP-Posting-Host: 75.167.99.73 User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <6da72874-50b6-459b-aee8-dacd86125ef0@googlegroups.com> Subject: video phone via landline From: Jason Yan Injection-Date: Sun, 29 Mar 2020 04:48:48 +0000 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Lines: 30 Xref: csiph.com comp.dcom.telecom.tech:364 My question may sound weird but I could not find a clue online and I am not= in telecom field. Hoping I can at least get some expert insight here. Than= k you very much in advance! Assume there is no internet at all (not even ADSL or DSL), and no cell phon= e next work at all. Is it even possible to make two video phones that commu= nicate purely through landline? I mean, just "invent" video phone and simpl= y replace your home analog phone, and video call another person who also re= place his home analog phone with video phone. It is kind of like video int= ercom but through landline (video intercom seems to use different wire), an= d it is two-way video instead of one way video plus one way audio like vide= o intercom. What I learned is that, the analog voice signal and digital signal (I assum= e video has to be digital) can both transferred through the first pair of w= ire (T/R) in a landline. Analog signal and digital signal can be mixed beca= use their frequency are very different. I understand that the bandwidth wil= l be quite limited, but I am fine with only like 200x300 pixel sized pictur= e, and with only 10 fps (frame per second) so hope bandwidth is not a real = issue. I also assumed there is no DSL or ADSL available, which means I cannot use = the existing TCP/IP protocol but need to develop my own protocol just for d= igital data transfer between two phones connected through a physical landli= ne. Is my idea even possible? I am thinking of this for seniors who are afraid = of any internet and smart phone thing and all they have is just the old ana= log phone and a landline. Jason Yan