In the example from last night that I posted about, I left a very important voicemail about someone's health just before I walked into a hospital where I knew my phone wouldn't work very well. I know that the recipient of my voicemail appreciated my effort in communicating the situation. He would not have known the urgency of the situation had we gone into the phone tag dance.
I completely understand that voicemail can be annoying. I often prefer other means as well. I'm just surprised so many would refuse to use it at all.
Many people refuse to call back numbers that are unknown to them. Others (myself) tend not to call back on a missed call without a voicemail or a text. I assume if you just call and leave no message, you'll reach out to me another way or it was just asking what was up.
The problem is that "Telco" hasn't existed (at least in the USA) since divestiture of Bell System. Tariffed services include access to the PSTN as in terms of trunk lines (esp. PRIs), which allow end users to control call appearance including specification of the originating Directory Number (DN) that is passed in the SS7 call setup message (ISUP). It is even easier with SIP trunks.
This is a problem similar to DNS spoofing. Often a large organisation will have an 8xx number (toll-free) which they wish to appear for CLID on all outgoing calls from every line, every office.
How do you validate whether the toll-free (or whatever) CLID number passed is correspondent with the actual number of the OUTWATS trunk (or SIP trunk) used by a given caller? Trunk lines need not necessarily have a DN assigned to them if they are purely for outgoing service.
You would need to setup facilities to "sign" each originating call with a cryptographic certificate assigned to the owner of the number passed and then equipment on each terminating set to validate this.
Telco (FSVO "telco") may well not be able to fix CLID, broken as it may be - they can replace it for all the good it does. But it's always aggravated me that they can provide ANI to 8xx customers. Way different service I'll grant.
In the age of caller ID, what's the point ? I can see that you called me, and call back.