olemus
telefonside aluseks olev sidetehnika haru
= the branch of communications technology underlying telephone communication

ülevaateid
https://refurbphoneexchange.com/blogs/phone-and-tech-blog/11979317-difference-between-analog-digital-and-ip-telephony

https://en.wikipedia.org/wiki/Telephony

http://www.asteriskdocs.org/en/2nd_Edition/asterisk-book-html-chunk/asterisk-CHP-7-SECT-1.html

https://www.pacnog.org/pacnog6/VoIP/PacNOG6_voip_telephony_intro.pdf

http://www.cs.columbia.edu/~hgs/teaching/ais/slides/2015%20AIS%20VoIP%200504.pdf

https://telecommetric.com/cloud-communications/the-future-of-telephony-trends-and-technologies-to-watch/

https://justcall.io/blog/voip-trends.html

vt ka
- mobiilside
- netitelefon