Both sides are barking up the wrong tree. A use case:
1. I'm on a massive international con call. One you need to be on because they actually call people out, and when you are "on" you better not do a gaffe or not have the answer.
2. I'm really backed up with email (because I don't give The Man free hours - e.g. none of this logging in on my own time bullshit)
3. Someone texts me.
4. I sit in a dead zone.
5. Text might take over an hour to show up on my mobile phone.
6. Meanwhile, if the texter called me instead, they would reach my voicemail.
7. The little red light on my phone lights up if I get a new voicemail.
8. I can winnow through / find the new vmail easily in my email stack (note - your company has to have it set up that way - all email and vmail in an "inbox" cloud)
9. I take one of my sides of my headset's headphones off.
10. Double click on the vmail and listen to it from my laptop's speakers (oh, yeah, don't get rid of the lap tops either! Dumb move Mr. Employer!)
11. Now that is some right good multitasking all you whipper snappers (and for that matter, all you Boomers who are still trying to figure out how to make this use case work).
12. Oh and then there is IM (on the lap top). That pops up instantly. No muss no fuss. Again, don't do BYOD (aka more employees doing stuff for employers on their own dimes, sinful). Give 'em laptops! BTW - steps 6 - 10 could all be completely on the lap top, don't even really need a desk phone at all.
One final comment. Texting has always been better in Europe and Asia than in North America. Here, it has only been recently that the phone companies don't completely rip off the subscriber for texting. Meanwhile over yonder, it's been cheaper to text than use voice for the past 10 years (maybe more). North American phone companies completely suck in this regard and several others.