You're at a major sporting or music event, or at a train station during peak hour, and try to post about it on Facebook but it fails.
Welcome to the 21st century, where 30.2 million mobile voice and data services operate in Australia – according to a new report by the communications regulator – and mobile networks struggle to keep up.
Just like roads during peak-hour, congestion occurs on mobile networks, and it's starting to become more noticeable, especially for those attempting to use them where large numbers of people congregate.
The congestion isn't expected to be solved in a massive way until at least 2015, when the spectrum ideal for 4G networks to be deployed more widely is made available, according to analysts.
After Fairfax Media ran a story about congestion affecting Telstra's 3G mobile network in Melbourne this week, close to 200 people emailed in – and 95 left comments online – about their experiences of mobile congestion, particularly congestion affecting data on their smartphones.
The complaints, which largely focused on Telstra in Melbourne but also contained nationwide feedback, ranged from poor internet service at the MCG, homes, the CBD and at train stations during peak hours.
Foad Fadaghi, a Telsyte research director, said congestion would only increase as devices such as cameras with cellular connections and connected cars started to emerge.
"There is a huge opportunity for carriers and technology vendors that can solve the congestion challenges," Fadaghi said.
Chris Coughlan, another Telsyte research director, said most telcos in high-demand areas had deployed most – if not all – of their 3G spectrum. This meant that in order to deploy more capacity they needed to "cell-split", which, according to Coughlan, "has issues, as the more cells deployed the greater the interference, especially with lower bands".
Coughlan said telcos would find it "challenging" to keep ahead of mobile growth in high-demand areas if growth continued at its current pace until 4G was more widely deployed.
In an interview, Mike Wright, Telstra executive director of networks and access technologies, said it was challenging to "predict whether there might be a shift in the rate of growth".
"A whole range of people might suddenly start using a mobile in an area, or we might get a time of day when there's a lot more people congregated. They're the things that make it a little bit harder for us."
Making matters worse, the spectrum required by telcos to deploy newer 4G networks more widely won't be available to use until at least 2015, after analog TV transmission towers are switched off.
Elise Davidson, a spokeswoman for the Australian Communications Consumer Action Network (ACCAN), the peak body that represents consumers on communications issues, said telcos were aware congestion issues could be frustrating and inconvenient.
She said telcos were working to ensure their customers could get mobile-phone coverage, especially at major events, where they usually deploy "cells on wheels", or "CoWs".
As well as deploying CoWs, carriers such as Optus are also working on ways to increase capacity on-demand to certain cell sites using new technology that can be deployed instantly.
But Mark Newton, a network engineer who used to work for ISP Internode, said it was difficult to see how "sprinkling magic pixie dust over a network" could "yield more blood from the stone".
"Ultimately mobile networks are constrained by two major factors: spectrum availability and backhaul capacity," he said. "A third factor is the density of base-station towers.
"[So] until [the] ACMA offers more spectrum [in 2015], nobody will be getting any new licences … and until carriers dig up the street for backhaul, they won't be getting any more of that either."
ACCAN's Davidson said congestion issues were likely to continue as more people bought smartphones and used tablets.
"Network providers are investing heavily in improving coverage for customers, but it is extremely difficult to keep up with our demand, particularly for data," she said.
Davidson added that customers could make a complaint to their provider in the first instance, and, if they were unhappy, speak to the Telecommunications Industry Ombudsman.
She said she believed people were becoming more aware of the fact that if they were at a place with a lot of other people, there would be congestion on mobile networks.
Complaint data compiled by the Telecommunications Industry Ombudsman:
Data compiled and provided by the Telecommunications Industry Ombudsman (TIO) shows that Telstra had 103 TIO complaints lodged against it nationally about slow mobile data speeds during the TIO's 2011-12 reporting period. The nation's No.1 telco also had 1161 complaints about coverage, 296 about dropouts, 268 concerning a customer's service being "fully unusable" and 63 to do with network outages.
During the same reporting period, Vodafone had 702 complaints lodged against it nationally about slow mobile data speeds and 14,094 complaints about coverage, 3436 about dropouts, 192 concerning a customer's service being "fully unusable" and 93 to do with network outages.
Meanwhile, Optus had 317 complaints lodged against it nationally about slow mobile data speeds and 8046 complaints about coverage, 1447 about dropouts, 194 concerning a customer's service being "fully unusable" and 56 to do with network outages.
Readers reacted strongly to Fairfax Media's earlier story about 3G problems in Melbourne.
"Telstra 3G is very flaky," wrote Melburnian Jenny Robins in an email, who lives north of the Melbourne CBD. "It's driving me to distraction."
Mark Traynor of Bonnie Doon, north-east of the city, uses a Telstra mobile broadband dongle and said that speeds were "appalling" and "slow" most weekends.
Mark Boldiston, who has a jewellery business in the CBD, said Optus recently allowed him to cancel his dongle after it confirmed its Flinders Street Station tower was experiencing what he said Optus described as "severe congestion". Boldiston added that Optus told him that they did not expect anything to change "for some time".
Leslie Harris of Werribee in Melbourne's south-west also uses a dongle and said his nearest tower was "grossly overloaded" and that Optus admitted this to him in an email. He is forced to use mobile broadband as he said Optus would not install cable where he lived.
But the complaints also touched on other areas of congestion around Australia.
Mike Connery of Leumeah, in Sydney's west, had an interesting analogy for his Telstra experience.
"[It's] so slow [it's] almost quicker to use a snail with arthritis," he said.
"[There are] more dropouts than a kangaroo with diarrhoea."
Poor mobile reception: what can you do?
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