How to send silent sms? urgent

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New member
Username: Bogiukas

Post Number: 1
Registered: 08-2011
Posted on Saturday, August 13, 2011 - 05:11 am:   


does anyone know how to send silent sms or sms type 0. I have tried recomended way using PID=40 but some of cellphones models recieve this message and reply me back saying what I want. I just testing numbers of active clients and dont want disturb them. is it possible to send in different way silent or ping sms which work on all cellphones? If I would try dont enter text=test in URL it could help?
please anyone help me very urgent.
thanks a lots.
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 3421
Registered: 08-2008
Posted on Friday, August 19, 2011 - 04:07 pm:   

Hi Bogas,

One thing to keep in mind is that when you send unusual SMS message attributes, those attributes may not be forwarded to certain operators. Gateways and interconnects have been known to strip unusual attributes.

The only way to see if that PID=40 attribute is actually getting set is to setup a GSM modem to receive SMS messages and check if the received message has that attribute set.

All that said, it wouldn't surprise me if some phones didn't simply ignore the PID=40 attribute.

As time has gone on, there has been more of a tendency of so called smart phones to ignore some of these odd attributes.

I decided to go back to the spec, ETSI GSM 03.40, and refresh my memory on this particular attribute. As I recall, it was never my idea to use it ... a few years ago, I think it was a customer that suggested it.

Here's what the spec says about this particular attribute:


A short message type 0 indicates that the ME must acknowledge receipt of the short message but may discard its contents.

Unfortunately, I think the key word in this sentence is "may".

This says to me that it is up to the receiving client, with the suggestion be that the client may want to silently discard the message. However, there is definitely no requirement that the client do this.

So if your experience is showing that some clients do discard the message silently, but some do not ... then unfortunately I would agree that this technique will not work for you.

Unfortunately, there are not good alternatives. In GSM environments, an HLR Lookup (which is an additional service offered by some SMS providers) can tell not only what operator a particular phone number belongs to, but also what operator the phone number is currently connected (e.g., if they are roaming) ... and by inference from that, whether or not the device is on.

However, as you can imagine, there are privacy issues associated with this, and depending on country/operator/service provider, there are some operators that will not report back the current connection status ... so you would have to test that for your service area.

Anyway, I'm reading a lot into your query, but I think an HLR Lookup service is what you want. The good news is that an HLR Lookup Query is generally cheaper than sending an SMS.

NowSMS Support