Plus just making an EQ curve that chops all lows and highs will give you a good LoFi sound.  Start with HiPass with a cutoff of ~ 400Hz, and then LowPass with a cutoff of around 2Khz. To go for the full Telephone effect, make a narrow notch of about +4 dB or so at around 500Hz.  Add some compression, low threshold (~ -20 dB ish) with a 4:1 ratio and boom - Lilly Tomlin is saying..."Number please!"

Sonitus FX EQ, the Telephone preset.

Just sounds like 'cowboy voice' to me.

Add a static loop trk

Also there's this: http://blog.cakewalk.com/5-tools-to-get-that-analog-sound-from-sonar/#more-22495 

Anderton
Depends on how you define "lo-fi." Like the distortion on industrial vocals? The sound of a singer shouting at a mic on the ceiling, like the original "Louie Louie"? Ambience that makes it sound like it was recorded somewhere strange? There are plenty of tools in SONAR which, if abused, can create very lo-fi sounds.
 
If you want more of a vintage vocal sound, try the Classic CA-X amp (in the Clean folder) with the drive turned down. The Jazz amp might also be a good choice.
 
For something more extreme, some of the processors in the Anderton Collection can be converted into Agents of Destruction without too much effort - Try Drum Loop mangler for angry aliens, or Hardcore Drums. The VoxTools FX chain has a Mayhem module that's sort of early NIN-ish. 
 

Sorry to be a dumpkopff, but don't find the Classic CA-X amp anywhere (would it be in Studio X3?)  and where would I find the Anderton Collection?

Guys, thanks much for the input... in case you're interested.....
Tried a whole bunch of suggestions, but nothing seemed to appeal to my ears. The PC stuff in Sonar just sounds too phony to my ears for this purpose. The BT Analog Valvedriver ADR-2S seemed to do some of it, but was too intrusive it seemed. I kept thinking that re-amping would do the trick, so I just tried a few guitar amp plugins for the heck of it, and Poulin Lextac seems to get pretty close to what I'm after...  not spot on yet, but just off the cuff I can dial in a PA-like tone with variable grit / distortion that's not too bad.  Puts a different spin on the vocal track. 
Amplitude free didn't seem to have what I was after either. 
 

The CamelCrusher works pretty good for the type of thing you are asking about ….
 
Kenny

What a tease. CamelCrusher like the rest of Camel Audio is no more...at least on a PC.

scook
What a tease. CamelCrusher like the rest of Camel Audio is no more...at least on a PC.

@scook 
I'm sorry it is not meant to be a tease …I was able to find it right here
 
http://www.audiopluginsforfree.com/camelcrusher/ 
 
when I hit the download button it lead me to here 
 
https://www.dropbox.com/s/3k0iy6v3pjxfoaa/camelcrusher-win_mac.zip?dl=0 
 
disclaimer  ,
I'm on my Mac right now so I don't know if this site has any cooties ….I did down load it and everything did show up 
both PC 32 , 64 and Mac ….
 
Kenny