What kind of notification methods do you (and I) know about (SMS, voice, etc.)?

Question

Notifications

Good night,
Technology does not stand still, however, people's notification options do not change much. Or are there new inventions? I am especially interested in methods suitable for age-appropriate recipients.
From myself, I will not just ask a question (look for a benefit for myself), but I will also try to systematize what we have and estimate the cost of such notifications (maybe there will be something useful for you as well).
So, there are 5 main notification channels:
1. Manual voice calls to people, we use volunteers for this, since they are available. Expenses - paying for phone calls, chocolates =)
2. Automated calling by "automatic informer". Calling is beneficial in case of notifications to landlines. Usually we have the efficiency of calling to fixed numbers about 30% (unsatisfactorily low). In addition, recently our provider of this service, MCS, ordered a long life, without even bothering to return the money from our account in the system before the termination of its existence. Ugly...
3. SMS messages. There are two delivery options.
3.1. Very fast dispatch. It is done through special offices, such as Zanzara, etc. (very expensive, from 1 ruble to 1.5 per SMS, everything is serious).
3.2. Independently, through a usb modem + SIM card and special software, such as free JuiceSMS. So slow! You can easily spend 2-3 hours to send out 300 sms.
Here you need to make a digression on the cost. It all depends on the provider and the tariff plan/options. My know-how, option night sms-unlimited tariff SuperMTS (provider keep silent, "surprise" 8-). Pay something like 150 rubles a month and send about 500 sms a day (from the hesitant words of technical support) without fear of being blocked for spam. Unless, of course, you don't send spam. We do not send it out, we have civilized notifications about what people need. Cons - SMS at night age subscribers are sometimes scared, some swear. If you have similar calculations (if you do such mailings) please share your figures/know-hows =)
3.3. What are push notifications and are they suitable for such tasks? IMHO for age - no.
4. Information letters by traditional mail (Russian Post). Costs - for printing invitations + envelopes with stamps. Envelope printing can be done automatically from the database. A good option if there is time a week or two before the event that we are notifying about.
5. Pigeon mail can perhaps be ruled out as not particularly reliable. WhatsApp / Skype / Viber - not suitable for age groups. Is it possible to send SMS via SIP, what are the costs? Notification through the welcome message of the corporate PBX (suitable only with a good incoming flow of calls). E-mail alerts - usually not very effective either, especially if you send a lot of letters, the probability of getting into the stop list and spam is extremely high. Also, older friends don't often use/check e-mail.
This is the oil painting in my opinion... Feel free to complete it...
Any of your comments would be welcome, thanks for taking the time to read. Good luck

Answer 1

I'm the developer of PushAll.ru, try it, it might suit you, these are Push notifications for computers and smartphones. It comes to Android through an app or through web pushes to mobile chrome, to a computer through a chrome add-on or web pushes. And to any device through the telegram bot. The user himself chooses through what and how to take it.
"IMHO for age - no." Well, why not, the "age" sit at the computer in classmates, turn on the push is a couple of mouse clicks.
And cheap android smartphones are already replacing the usual mobile phones for everyone. The application is simple. without it, web pushes are also included in a couple of clicks. If you have any questions, please contact me.
And do not miss the audience on computers, in our system, according to statistics, 50% of users from computers receive push notifications.
By the way, you can combine it with other methods if you have very few pushes per day, and especially if it is non-commercial use, then everything will be free for you.

Answer 2

Now many people have Viber, they can try to do mailings through it somehow.