Is SMS Reliability a Problem?
Text messages are all about instant connectivity and fast responses. They’re used in marketing, political campaigns, emergency alerts and subscribers’ everyday conversations.
But what if they’re not reliable?
Telcordia argues just that. A survey of attendees at Mobile World Congress and CTIA’s spring show in Las Vegas found that 82 percent of respondents from 75 different countries who had sent an SMS or MMS message in the past year said their message did not reach an intended recipient.
Telcordia believes the issue lies with number portability: SMS aggregators lack sufficient routing data needed to connect messages to numbers that have been ported from one carrier to another.
“Messages are being sent to the wrong carrier because subscribers have ported their number. The message can end up getting dropped,” says Joel Fisher, vice president, Marketing, Interconnection Solutions, Telcordia. “There’s definite room for improvement in message completion rates.”
The study’s methodology admittedly was less than scientific: Telcordia said it surveyed just 500 people and relied on self-reported information. The survey also was self-serving: Its results demonstrate the companies should use subscriber database technology – which Telcordia just happens to provide - to improve delivery rates.
Despite the survey’s methodological shortcomings, Telcordia might be onto something. The findings are reflected in part by SMS/MMS delivery rates monitored by Keynote, which uses live, remotely controlled devices placed around the world to monitor real-life delivery rates of text and media messages.
The company, which works with AT&T, Verizon Wireless, Sprint and T-Mobile, says the vast majority of text messages go through. “As far as SMS goes, most of the time it is in fact reliable in the sense that it will always get there,” says Ken Harker, Keynote’s senior manager of mobile and Internet technologies.
That said, things get a little hairier when it comes to delivering text messages between networks. In February, Keynote said the worst rate of SMS delivery between operators’ different networks resulted in one out of 500 text messages getting lost.
Delivery rates worsen again when it comes to MMS messages. Between carriers, up to one in every 150 MMS messages were lost in February. Harker does not attribute this to capacity issues, but rather to the various moving parts needed to get an MMS message to the right destination.
“There are more moving parts behind the scenes and you have the added complexity of managing the actual attachment along the way,” he says. “SMS messages are very small things that don’t require the data connection to be open as long.”
Harker says the issue of delivery rates pales in comparison to slow and delayed message delivery. “There are two problems: to get the average delivery time as fast as possible and to get that time consistent so that no one user has a bad experience,” he says. “We’ve found that latter part is the hardest.”
According to Keynote, one in 100 messages takes longer than a minute to arrive for almost all the Tier 1 carriers in the United States. At one of the country’s four top carriers, that figure hit 3.99 percent in February. Keynote declined to name the operator for reasons of confidentiality.
“This can be problematic because of the way messages are used: it’s like a full minute delay in the middle of a conversation,” Harker says. “You might consider a 60-second delay as failing your customers.”
The Problem’s Complicated Root
Figuring out why messages get delayed or dropped is a complicated task. Message aggregator Syniverse admits that aggregators that don’t use databases of ported numbers and that fail to back up their networks appropriately could be responsible for dropped messages.
“If there is not a database dip to make sure you have a valid subscriber number, then you have a problem. Some aggregators do not access those databases,” says Syniverse CEO Tony Holcombe, adding that some aggregators “don’t do appropriate geo-redundancy” to back up their services in case of emergencies.
Holcombe noted that aggregators' capacity issues can cause delays.“We know when someone is having problems getting messages delivered because they cue up,” he says. “When the pipes open up, they go through, so there might be timing issues with some aggregators in this regard – although it’s much less of a problem now that capacity has caught up.”
Sybase 365, which handles inter-carrier SMS/MMS, says “way less that one percent” of the messages going over its systems don’t arrive at their intended destination – and the error is usually due to disallowed content or a mistyped phone number. Like Syniverse, Sybase is held to standards of 5-nines reliability: 99.999 percent of the messages they handle are delivered successfully.
However, even a minute percentage of the billions of messages sent every month can result in thousands of missing SMS and MMS messages. “If you look at a big enough sample, you’re going to find things that don’t go through,” says Bill Dudley, who handles product management at Sybase 365.
When things do go wrong, it can be difficult to pinpoint where the error occurred, as message aggregating companies like Sybase and Syniverse don’t have the visibility to know exactly where problems occur in operators’ networks.
“There isn’t one big area where messages get hung up,” Dudley says. “It could the carrier, it could be latency it the network, something could happen with the message’s content.”
Mark Beccue, a consumer mobility analyst with ABI Research and former employee of Syniverse, points out that aggregators are bound by contracts to successfully deliver messages. Also, he doubts networks are to blame. Rather, he points to the multitude of handoffs that occur between operators, aggregators, users and content providers. Glitches anywhere in the system – whether it’s user error, aggregator error or a capacity problem – can result in messages being delayed or lost.
Still, Beccue holds substantial doubts as to whether text message delivery rates pose an issue for the industry at all. “I don’t buy that it’s a systemic problem… If any of the top four carriers had anything close to eight percent of text messages dropping, they’d have a problem,” he says. “That’s not something they can live with.”
A spokesman for Verizon Wireless said he hadn’t “heard this is a major issue” and did not provide additional information by press time. Sprint and AT&T did not reply to requests for comment.