My VOIP provider gives 32 free blocks. Works great, but 32 is entirely insufficient. They also provide blocking for any caller who doesn't display a legitimate phone number. (Spoofed numbers are considered legitimate. I have been receiving calls from my own landline recently). The caller receives a message stating they must call back after temporarily releasing their number with *82. Works great! I never get Private, Unknown or Out of State calls anymore. They are blocked at my providers facilities. I have know knowledge of the calls without checking my online records.
I have a similar model of the same brand phone you have. 250 blocks which I'm using up at an alarming rate in just over a month.
Like you I thought the call was answered and then disconnected, but that's not how it works. I don't use the phone's built in answering machine. I use my providers voicemail system. That may or may not make a difference in what I'm going to explain. Maybe I'll test it calling from my cell.
What I found is robo-callers hang up on 4 or fewer rings so they never get to leave a message because I set my voicemail to pick up on the 5th ring. If you ever watched a Blacklisted call come in, Caller ID shows “Blocked Caller” until they disconnect. It stays lit for the time of 4 rings, not 1.
Politicians are patient so this election cycle they are leaving plenty of voicemail even though I have blacklisted their number.
For these 2 reasons I believe the phone is only silencing the ringer. It isn't disconnecting the call.
Again I may test these ideas after Blacklisting my cell number.
Although the factory settings are for 1 ring, there is also an option to silence the 1st ring. It's listed in the owners manual. I haven't been able to enable this option and have called the manufacturer who hasn't replied. If a number has been Blacklisted, if prefer no rings. I can always check Caller ID for the day's callers which includes blocked numbers.
Blacklisted number called our DNC registered landline on 10/07/2014 @ 05:17 PM from Kirkwood, MO. The phone never rang.
I am 29+ and must have graduated to the geriatric call list because the last 2 days I'm getting pain cream calls and medic alert calls for the first time.
It does disconnect after one ring. The manual states this; and I tested it by temporarily blocking my own cell phone number. It hung up after one ring.