Yes, it is a legitimate sales number.

It comes up as “toll free service” for contact information on my phone. It never leaves a voice mail. If it is Koodo, they aren't very  bright  I’m not using identifiers or authentication methods Eg. Text “Koodo will be calling you at 00:00 for (x) purposes”. 
 

I just hang up. Toll free could be a spammer, scammer, call from a jail… if it is Koodo, they need to up their calibre. 

There are certain numbers that may show Koodo for their marketing calls. You can refer to the link below to see which ones are currently used by them. 

I received that call too. Tried to offer to lower my bill but cut both mine and my wife's data plus offer me security cameras included supposedly on our new plan. When he asked about my account, I backed out and dropped the call. Not comfortable unlike before KOODO comes out when they call. This one was toll free serv. 

I get calls from this number and my phone automatically flags the number as a spammer. Then it leaves a blank voicemail message.

Can't explain the blank voicemail. But as you can see, it is actually Koodo.