What does a "unselected carrier" error message mean? - telephony

The message goes like this:
We're sorry this is an unselected carrier. This call cannot be completed as dialed. You may designate a carrier to handle this type of call by calling that company or your Verizon business office during regular business hours. To place this call in an emergency, just dial zero.
Any help understanding the underlying process that creates this error would be appreciated.

It is a telephone service message for the end user.
It could be provided when multiple carriers are necessary to complete the call.
You always have at least the local carrier directly managing the phone.
For long-distance calls, it is possible to select another carrier where both carriers cooperate for the call completion.
In your instance, I guess an automatic selection is used but has been disabled.
Or it could be also that a wrong carrier code has been dialed for this particular call.

Related

Twilio Studio Flows working with one number and not the other

I created two Flows in Studio. One is a simple call forward, the second is a split to forward call or leave a voice mail.
I have two cell phones/numbers with separate companies(in Canada - Rogers/Shaw) If I use the first phone number(Rogers) the flows do not work. I get an automated message that says "The person you are calling isn't accepting calls at the moment." or "The number you are calling is not in service."
If i change the forward to number in Flows to my second cell phone number(shaw) then both the flows work. I even tried forwarding to my work phone and it works.
Basically forwarding numbers in Flow to my ONE cell number only does not work. Would anyone know what may be causing this? Could it be an issue with my cell phone or cell phone provider somehow blocking the calls?
Both of my cell phones are iphone 12s
Thank you

What use cases are there for Early Media with IVRs?

I would say that the following are valid use cases for Early Media when used for IVRs:
Filtering
Disconnect incoming calls based on certain criteria (such as callers from a specific area code, or to play a message before hanging up on after hour callers).
Rate limiting
For example to limit the number of simultaneous callers, where the excess calls are either disconnected, or placed in a queue. (I'm not sure if the queue example is possible though without answering the call.)
Are there more?
Some links that were helpful:
https://www.dialogic.com/webhelp/csp1010/8.4.1_ipn3/sip_software_chap_-_early_media.htm
https://wiki.asterisk.org/wiki/display/AST/Early+Media+and+the+Progress+Application
https://freeswitch.org/confluence/display/FREESWITCH/Early+Media
3) Legal: in some countries it is illegal for a call center using payed line (caller pay per minute) to accept a call without sending it straight to an agent. So you can't accept the call, give the user some waiting music for 15 minutes (and make them pay for the privilege of waiting as well).
Result: you don't accept the call. However, this creates a new problem: if the caller only hears the ring back tone for those 15 minutes, he/she will assume no one will answer and hangs up.
Using early media, you can give them the traditional "your call is very important to us, please hold on"-type of experience without accepting the call and without starting to charge money. Of course this also depends somewhat on how much the provider is willing to tolerate, as this can also affects their income (depending on their own business model).
4) Comfort: you may not be aware of this, but the sound you hear as caller when the other side is ringing (ring-back tone), is not universally the same throughout the world. A company with a global number may wish to use early media to provide a ring-back tone more familiar to you, depending on where you are calling from. It was always a bit niche of a concept but some target audiences are statistically more likely to hangup if they hear an unfamiliar sound. 15-20 year ago this might have been a concern to some, but in the era of smartphones and internet calls, I doubt anyone really worries about it anymore.

How to tell the difference between an offline and online mobile phone via sip?

For a toy project I want to find out if a mobile phone is connected to gsm or not. So I thought "Okay, let's use my local sip provider and see".
But in both cases, the thing goes like this:
I send an INVITE
0 s: I get a 100 Trying
5 s: I get a 183 Session description
I get an audio stream, in the one case with the ringing, in the other case with a "The person you are calling is…"
If I wait long enough (~ 40 s), I get a more appropiate status code like 180 Ringing.
Audio analysis is not an option, really.
Any hints on where to go now?
(I used twinkle for testing and a local german sip-provider.)
This issue is endemic in the way telephone networks work, and is not specific to SIP or IP. It's why, when you place a call to another country and the number is busy, you might sometimes hear your local country's busy tone, or you might hear a different busy tone that comes from the other country. In the latter case you cannot detect except by audio analysis, what the problem is. In SS7 and ISDN we speak of Q.931 cause codes instead of SIP error codes, but the principle is the same.
There's an argument to be made for configuring telephone systems to emit status codes instead of audio error messages. For callers using normal phones, the originating switch (the one closest to the caller) can then map that code to the appropriate spoken error message or audio tone. That way, when the call is being placed by software rather than by a person, the software can have access to the actual error code right away.
On the other hand you can also argue for having the remote switch (the one nearest the destination or the one that encounters the problem) speak its own error message. That switch knows best what the actual problem is. For example, a mobile operator can emit a spoken error message saying that the mobile phone you are trying to call is currently out of range. There is no Q.931 code (or SIP error code for that matter) with that meaning. It could return 27=Destination out of order?? Or 35=Destination unattainable?? Both of those codes are so esoteric, who knows what error message the local switch would translate them to (in practice: probably just a reorder tone, which is really user-unfriendly to a human caller). And when you try to map Q.931 cause codes to SIP error codes back and forth, even more information is lost because the codes really don't match up well at all. It's likely to be a much better user experience for the caller if the remote switch just plays back an informative, appropriate, recording which describes the problem.
Since there is this dilemma (arguments on both sides), we can conclude that this will not likely be resolved by completely standardizing on one way or ther other way anytime soon.
Anyway, sometimes this is configurable: your SIP provider may be able to configure your trunk for coded errors instead of recorded messages. If they offer this (some do), it's worth a try to set this option. But results will vary: this option only affects its local behaviour. In general if you want immediately call clearing with cause code and are instead getting a recorded error message from the other end, you will not be able to do anything about it, because the switch that makes the decision on which way it's going to respond is the remote one.
When using the audio message method, a proper Q.931 cause code or SIP error code usually comes eventually (after the recording is finished), but as you point out, it's probably too late by then.

Asynchronous Calls (specifically iOS geocoding)

I'm wondering how to deal with this particular issue:
I'm creating a place object, which gets initialized with a geographical lat-long pair. Then I use the iOS geocoder to get an address for that coordinate. I want to set that address to one of my instance variables. However, this asynchronous call doesn't get completed in time, so when I instantiate my object and try to display the address, it hasn't been done yet. What are some strategies to deal with this and similar problems?
Thanks! Merry Christmas!
I don't feel like creating an extensive answer on Christmas Eve so I'll give a brief answer here for now, and edit it later if you've got questions and/or want more details.
Asynchronous requests all have delegate/protocol methods that let you know when the request has failed or succeeded. You should use the NSNotification API and register any object that needs the address for a notification that's triggered when the object completes the request. When the object receives the notification, it can then configure its views or whatever it needs to do. In the requestDidFinish (or whatever) method, you should send the notification.
Check out this article for details (as well as some cool stuff about threading!): http://www.raywenderlich.com/4295/multithreading-and-grand-central-dispatch-on-ios-for-beginners-tutorial

How would I get SMS/Phone events, and act on them before they're sent to the system apps?

I'm trying to develop an application for a jailbroken iPhone similar to Mcleaner or iBlacklist.
What I want my app to be able to do is intercept SMS or Phone events and handle them before they're sent to the appropriate receiver. So for example, I want the application to get an SMS event, compare the sender to an array of numbers, and either process the data or ignore it and pass it off to the SMS app.
In MCleaner, you can define a blacklist of numbers, and if a text message is received that matches the blacklist the user won't get an alert from the phone and the data is instead handled by MCleaner.
How would I go about getting these events, and further, how would I get these before the appropriate apps receive them? From what I understand, I'd need to become a first responder for these things, but I really have no clue where to start. I can't seem to find any hints on how I'd go about this as this app will not be calling apple classes to get the data..
Thanks.
I can only guide in with this, sorry, the code isn't mine to give.
In memory, all the action calls are all just pointers. What you have to do is over ride the pointer to make it point to your own function. Once you do that, you do w/e you want in your function, and then call the default function call. This ensures the integrity of the action calls and allows you to intercept the actions.
You need to use the CKMessage class.
Check this out: http://hexorcist.com/private_frameworks/html/interface_c_k_message.html
and this: http://www.ifans.com/forums/showthread.php?t=232745