Call and sms blocker with phone appearing switched off

[lnviper88]

Hello.
As the title says, i am searching, with no luck till now, for an app which will block certain numbers from calling and texting me, but without them knowing that i blocked them. I want my phone to appear switched off specifically to them without their calls and texts arriving at my phone at all.
My problem is that every call blocker app i 've seen and used, assumes that someone wants to block a specific contact forever by blacklisting him, but that's not always the case. Depending on the situation, there are days that i want to be able to be contacted only from very specific numbers by temporarily blocking all the other numbers without them knowing. Or there are instances i just want to be able to use my smartphone to browse the internet for a couple of hours without anyone bothering me at the time. If you blacklist a person, he will assume that you dont want him to contact you anymore and this will be highly misunderstood, because with these apps it appears to them that the phone is ringing one time and it hangs up. It's a different thing to not want to be temporarily bothered by some people for some hours or a couple of days and a different thing to want to blacklist a harrasing person forever.
That's why i 'm searching for a call and sms blocker that will make my phone appear switched off to specific contacts and will be able to unblock them later when i wish to, without creating misunderstandings, but i haven't find any apps with this purpose. Any help?

 

[Hadron]

I don't think it's possible for SMS. If the phone is off the message won't be delivered, whereas a message blocking app just hides the notification and message from you. So if they have delivery receipts on they will know the message arrived - we did some experiments with someone who had this specific question a few months ago. If they don't have delivery receipts on then they won't know whether you received it or not anyway.

For calls what you want is to divert the number straight to voicemail, as that is what will happen if the phone is off. It's straightforward to divert all calls to voicemail, but I don't offhand know how to divert an individual caller.

 

[lnviper88]

Thank you for your answer.
You are absolutely right about text messages, the apps just hide or delete the sms after it has arrived on your phone and the sender will be given a notification that you received it, which is not much help. These apps are useful when you want a number blacklisted forever and you dont care hiding the fact that you blacklisted this number, but they are not much help for the purpose i described in my first post.
I was wondering, if anyone knows and cares to answer, why isn't it possible structurally for a cellphone to just be switched off to specific users you choose to? I mean, for a call to be made from someone, the signal from the call arrives at your phone and the origin gets recognized, and after that the phone rings, isn't it right? So why isn't it possible to just get recognized and automatically reject it without ringing at all? Same question goes for text messages, why isn't it possible to just recognize the sender and automatically reject the message before it completely lands on your phone?

 

[Hadron]

Nobody else is trying this, so here's my best guess.

For SMS, I'm not sure there is a mechanism for a phone to reject an SMS - reject means reject by the network (invalid address or undeliverable for some reason). In any event, SMS receipt is handled by lower-level system software rather than the message app (which is just a front-end), so no user app can change it. But if it did, what could it do? Hypothetically you might hack it to not report that the message had been delivered, but if the network thought that the message delivery had failed it would try again (and if the carrier found out you'd changed the way basic network interfaces were handled they'd be justified in blacklisting your phone). But all of that assumes that "before it completely lands on your phone" is an option, i.e. that there is a point where the information about the sender has been received and but the message itself has not been delivered, during which time your software can act. Given how small the data package is I'd expect the whole lot to be delivered in one go and that to be the end of it.

As for calls, you are describing the sequence as seen by the recipient of the call. Now I don't know how it is at the level of the telephony systems: I could imagine that that goes more like "connect to phone, send caller information and await response" (where response is "pick up" or "reject"). But the "ring" that the caller hears is generated by the network, so it's possible that the act of connecting at all generates the first ring without waiting for the phone's response. If that is the case (and again, I'm speculating on this) then no user app could do anything about that. As the connection sequence will be specified in the network protocols you certainly won't be able to change that, whatever it might be. Call diverts avoid this because they are handled by the network and so never reach the phone, but you'd need the network to support selective diversion of particular callers (certainly not impossible, but if it doesn't exist it would cost them to set it up, and I can imagine they'd need a strong reason to make big changes to network systems).