The best replacement for voip is pbx.

The best alternatives to voip are rated as following:
★★★★★  pbx
★★★★  landline
★★★  pstn
★★★  pots
★★  ip telephony
★★  skype
★★  sip
★★  analog
★★  tdm
★  digital phone
★  magic jack
★  pri
  volte
  cell phones
  isdn
  vonage
  regular phone
  telephone
  voice over internet protocol
  home phone
  digital phones
  phone line
  land line
  circuit switching
  ip pbx
  cell phone
  landline phone
  centrex
  phone
  pbx system

Your alternative for voip is not listed? Suggest!
Speaking about voip, one probably shouldn't forget about google voice.

Other search terms related to voip and their ratings are:
★★★★★ google voice
★★★★★ fax
★★★ sip
★★ qos
★ broadband
★ mpls
★ 911
★ satellite internet
★ e911
★ asterisk
alarm system
pbx
You have in mind a companion for voip and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of voip in all years. Click on graph for more.
voip
pbx
landline