The Jakarta Post released some numbers on Tuesday from Nielsen’s upcoming Southeast Asia Digital Consumer Report which shows, among other discoveries, that Indonesia places last in the region for country-wide internet penetration but nearly half of the country’s Internet users go online from mobile phones.

The report found that only 21 percent of Indonesians aged between 15 and 49 access the internet whereas in Singapore it’s 67 percent, 38 percent in Malaysia, 33 percent in the Philippines, and 31 percent in Thailand. The regional average is 38 percent. The report does not provide numbers for ASEAN’s other members.

Nielsen discovered that 48 percent of Indonesian internet users are on mobile phones with an additional 13 percent using other handheld devices. In terms of percentage, this surpasses all other countries in the region with only 36 percent of internet users in Thailand and 35 percent in Singapore preferring to use mobile phones.

Thanks to the lack of availability of high speed landline connections such as cable and ADSL across Indonesian homes, the results are not surprising. Coupled with the rise in affordable Internet plans from mobile providers and increasing number of sub-$200 phones, it’s clear that mobile internet access is a high growth area and will remain so for the foreseeable future.

Despite the proliferation of mobile internet, Internet cafes are still the dominant locations in which Indonesians go online. While 67 percent of other Southeast Asians access the Internet from home, 66 percent of Indonesians go to Internet cafes, the report says.

What is not yet revealed however, is the time spent on each terminal. Since mobile phones are much more personal and obviously carried everywhere, it’s very likely that people spend more time online on their mobiles rather than sitting in a public cubicle.

For its 12 month projection, Nielsen’s survey found that mobile internet usage in the country will rise to 53 percent of all netizens while other handheld devices will grab 30 percent of the market.

Still on mobile browsing, Opera’s latest State of the Mobile Web, released in June for the month of May showed quite an increase from April. Page-views per user went up from 447 to 523 while data transferred per user for the month went from 5 MB to 6 MB. Indonesia’s usage of Opera mini is second only to Russia.

It’s worth noting that the increasing use of mobile devices for internet access does not preclude people from also accessing the internet using traditional computers. The numbers however may not overlap that much seeing that there are upwards of 170 million mobile phones in the country and only 15 million computers according to MobileMonday Indonesia organizer Andy Zain.

Of course, not all of those devices are connected to the internet but it should provide some sort of basis for reference as to the massive gulf between the distribution of mobile phones and computers in the country.

In its other findings, Nielsen also discovered that only 19 percent of Indonesians use the Internet from home, while 22 percent go online from the office and 14 percent from educational institutions. As with the device breakdown, these numbers are not exclusive of each other.