Can Whatsapp send an sms to a cellular number?
No, but Google Hangouts can. It does IM, video calls and SMS.
OK, this is serious thread drift, but here’s another vote for WhatsApp. Use it regularly, and am well beyond 20 ;-( as do many of my equally age-challenged friends and business partners. And yes, you can send pictures of private or other parts, even airplane parts 
Google Hangouts can. It does IM, video calls and SMS
How is the SMS delivery funded? They can’t do it for free – not in Europe for sure.
Unless somebody drives Whatsapp with a bit of software, it won’t be any good for aviation data.
But also I am puzzles about how Whatsapp supposedly works as described. One cannot just hammer the socket (the internet interface in the client device). Once the connection is lost, the IP is probably lost and then you cannot receive packets, and you can’t send any because you don’t have an IP anymore to which the other end could reply. I am wondering whether the reports of Whatsapp working at FL200 or whatever are merely correlations between particular flight profiles/routes and where a particular type of GSM tower happens to be installed (i.e. Germany!).
One could do a bit more with UDP packets (no TCP/IP protocol to keep going over a crappy connection) but you still need an IP even then. That would need a private server of course. A fixed IP would solve it and I think the Iridium based services use fixed IPs.
For receiving, it uses the push notification service inherent in the OS. If a connection is open then fine it’ll use that, but if not it will use push. It has to, otherwise it wouldn’t receive messages when it wasn’t running in the foreground. For sending, it will just try to establish a new connection.
Peter wrote:
How is the SMS delivery funded? They can’t do it for free – not in Europe for sure.
Google do send SMS for free in other scenarios, for example, for calendar reminders. Though, apparently they’re scrapping that, but they have done it for years.
How can google deliver an SMS to you if it was sent the way every SMS is sent i.e. the sender sends it to his cellular network?
I don’t know about other countries but in the UK there is no way to virtualise mobile numbers. Only geographic ones can be done e.g. I have a fax2email service on a Brighton (01273) number.
Though, apparently they’re scrapping that, but they have done it for years.
I am not surprised – I don’t think SMS can be done long-term for less than a few pence a message. By “long term” I mean without advertising or getting somebody else to pay for it.
I also really struggle to see how push notifications are going to work at high altitudes. They do rely on the OS having an internet connection, with everything that follows from that i.e.
Peter wrote:
keeping that IP as the aircraft’s location jumps across many cells, losing the signal at times
3G/LTE networks preserve a device’s IP address for a long time, across many cell handovers. The IP network is decoupled from the 3G network and the cells share common gateways/routers. The counterpart routes the traffic to the phone provider’s infrastructure and the network then figures out how to forward that to the phone.
I also really struggle to see how push notifications are going to work at high altitudes. They do rely on the OS having an internet connection, with everything that follows from that i.e.
It’s all about smart retrying, pushing and polling. Eventually you get the data through. Very simple applications perform a socket call and if it fails, the app shows an error. Smarter apps have retry and queuing logic.
Peter wrote:
How can google deliver an SMS to you if it was sent the way every SMS is sent i.e. the sender sends it to his cellular network?
They only deliver them via SMS.
Peter wrote:
- getting a GSM signal
- getting a mobile connection over UDP, long enough to get an IP assigned via DHCP
- keeping that IP as the aircraft’s location jumps across many cells, losing the signal at times
Apple’s push notifications use TCP. The last of these is a red herring – it doesn’t need to keep an IP, because the next time it gets a connection it will get whatever is waiting for it. So really, the question is all about the first one – getting a good enough GSM signal to make a 2G/3G/4G data connection. And because it’s sporadic that’s why something which “keeps trying” on the send, and uses push notifications on the receive, works better than the alternatives.
I crossed with Achima’s post, though nothing either of us said is contradictory. Point is, if you can get any kind of connection and you keep trying, you get through. So “any kind of connection” becomes the important bit.
I was I my local pub a while ago, noticed my phone said it was on 4G, and did a broadband speed test. I got 29.44 Mb/sec download and 5.97Mb/sec upload.
That was in a rural pub, in a village of about 200 population about 9 miles from a big town.
There is no doubt that 4G is very quick, when it works.
That also means that if you can get it to work while flying, even for 10 seconds, you get a lot of data moved in those 10 seconds.
The problem I see is that none of the “normal” apps will detect and grab that 10 second slot. If you refresh a website, the browser just stupidly sits on the TCP/IP socket with a timeout of some tens of seconds. An email add does the same, though they can be set up to check email every 1/10/whatever minutes (but that’s no good if the 10 second availability happens to fall between the retries )
What is needed to improve the situation is a low level driver which monitors the actual GSM signal and, on the assumption that GSM=data it presses the refresh button on the browser (or the Submit or whatever button in the website you are on). And same for email if you want email. Obviously nobody is going to write such a thing, but a specific app could be thus written (maybe Whatsapp does that).
One problem is that evidently the assertion that GSM=data is not true. On much of a flight at say FL100 I see several bars of signal but absolutely no connection can be made. Not even SMS. It could be that – especially in the absence of LTE/4G – the cellular system decides to ignore a client which is jumping between too many towers. Some insiders have told me this does happen. But also it is evident that having a signal does not mean the phone does anything; Justine’s Iphone4 was happily doing that in the middle of Brighton… also Vodafone UK had this issue in the Shoreham area about a year ago; they fixed it eventually.
Also I suspect the availability of 4G affects whether plain old SMS (the basic GSM version, not SMS over 3G/4G) is available, which might explain why my Nokia 808 (no 4G support) was pretty good on SMS and usually you could get messages up and down, eventually, anywhere up to FL200. It had hacked firmware which retried every 3 minutes, for ever, so on a say 4hr flight you would eventually hit a “slot”. The old phones had config for whether to route SMS over 3G or over GSM only, and I bet you this was there for a reason. The UK “3” network was for a long time notorious in this area because IIRC they contracted out non 3G traffic, with mixed results (it was near-useless in UK countryside which is mostly GPRS only). But the new phones have all been subject to the “usability committee” treatment which is to remove all config features which a complete idiot can’t understand My new Samsung S6 can be configured to send everything via GSM only (i.e. you will get no data whatsoever, apart from possibly the ancient 9.6k dial-up which I used 10 years ago, which nobody uses anyway) so I could test that on my next high altitude flight to see if SMS improves. But what a perverse way to go about it…
So I think the situation is more complicated, and probably specific networks are set up in certain ways which just happen to make it work, especially if you are in Germany.
On top of that you have the old issues that some networks don’t pass texts to others. This is rare nowadays. It’s common with satellite phones though.
