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Looping text messages are caused by a network fault

It ain't the server's fault, honest
Mon Jul 23 2007, 18:11
APPARENTLY THE SMSC - or text messaging server, is 15 years old today. And its creator, Acision, is adamant that the technology is foolproof. It's just the network which is at fault.

Acision's Steven van Zanen, was responding to a question posed by the INQ as to why several INQ readers have experienced an almost infinite text message delivery loop.

In such cases the message just keeps arriving time after time again on the recipient's handset. As the INQ surmised, this I because the SMSC is failing to receive an acknowledgement (ACK).

But as van Zanen pointed out, there's no discourse between two SMSCs - only the sender's SMSC is involved in a text transmission.

The ACK has to be sent from the handset and if the network is configured incorrectly, then it won't allow the acknowledgment through.

In the case of the INQ reader with an O2 handset, van Zanen pointed out that an ACK might go through as many as 50 hops to get back to the sender's SMSC.

But these guys don't sit still. Guess what? There's going to be an SMS 2.0. This will cover text messages sent over IP using SIP. And the standards are being formulated right now.

Some INQ readers may be puzzled to learn that Acision provided the first SMSC while the name is unfamiliar. The answer is simple.

The company is formed from various mergers. Ireland's Aldiscon - which we believe had the first SMSC, was acquired by Logica. And Logica then merged with CMG.

So two of the world's premier SMSC server providers have been merged to create Acision.

The turn of speed which these servers can now achieve is also impressive. Initially an SMSC could provide a throughput of 10 messages per second.

Nowadays a single rack can manage 16K messages a second. So it's just a question of how many racks do you want?

Oh. One last point. You don't get charged receiving a text message abroad as originally reported. A higher tariff onyour bill just means you've received a premium rate message (£1.50 in most cases).

And you only get charged that £1.50 jst once - after the ACK has finally made its way through the network. µ

See Also
O2 text centre goes into loop



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