When I was in Uganda I came across this 2-in-1 sim card at a mobile phone shop in Kampala.
The device allows you to switch between two sim cards without having to power down your phone and switch them manually. When installed, your phone gets a new menu entry that lets you configure a few settings. The most interesting feature to me was the ability to automatically switch between the sim cards at a fixed interval – for example, every 2 minutes – so you can receive SMS messages and / or phone calls on both lines. Obviously, it’s more useful for SMS messages.
One thing that I found interesting about the installation process was the tool used to cut the sim cards down to a smaller size.
The tool looks home-made to me but I’m not sure if the shop bought the tool from the supplier of the device or made it themselves. Either way I think it’s a cool hack.
I didn’t run across anybody else with this device in Uganda, however I did meet many people with multiple sim cards. It’s pretty obvious why people didn’t use this device – the cost really doesn’t justify the function. At 12 USD, that’s a third of the price of a cell phone, it’s just not worth it.
However, it’s worth exploring why people have multiple lines. First and for most is cost: if you phone somebody on the same network it’s cheaper. Cell phones themselves help out with this task. When you get a second or third line, you can request to have the same number with a different network code (the first 3 digits of the phone number). If you phone a friend with this specially chosen number on your second line, your address book entry will come up regardless of which line you use. This is good for the person receiving calls but it can cause problems if you try to phone somebody who has two lines. Because only one number is stored in your address book, you may think that somebody is out network coverage or their phone is off rather than just connected to another network. I ran into problems with this when I switched from regularly using MTN to regularly using Celtel (now Zain). When I phoned people using Celtel, my name came up on their phone but the address book entry was not updated. When they tried to call me back, it appeared as if my phone was off or I was out of network coverage – and therefore unreachable – which wasn’t the case.
A simple feature could be added to entry level or emerging market mobile phones to fix this. Any additional phone numbers detected for entries in a user’s address book could be automatically added as a second or third number associated with that entry. When a user tries to phone somebody with multiple phone numbers and the line is not active, the other number or numbers could be automatically tried or at least the user could be notified that the contact they are trying to reach may be using his or her second or third line. It would be nice if something could be worked out for SMS messages as well but that might have to be handled at the network level.
The second reason for having multiple lines – a reason that sometimes gets ignored – is network availability. Outside of Kampala, the mobile phone networks often go down without warning for many hours. I remember one time the MTN network was down for more that 16 hours. If you have a second phone line, you simply switch to a different provider and continue business as usual. Well, except if you need to contact somebody who doesn’t have a second line 
. The feature enhancement mentioned above could help with this situation if the person you are trying to contact has a second or third line. The enhancement might even encourage more people to get a second or third line to improve the reliability of their communications with other people.
The third reason that people have multiple lines is network coverage. Once you get out of the big cities and towns, coverage is spotty and not consistent across networks. For example, your home village may have coverage with MTN, but the village where you need to attend a funeral may only have coverage with Zain. In this case you merely swap the sim card with the one that is stored between the phone battery and battery cover and continue on.
Another relatively inexpensive feature that could be added to entry level or emerging market mobile phones is space for, or a little holder for a second or third sim card between the battery and the battery cover. I noticed that there wasn’t always space for sim cards in this location or that placing sim cards there would start to wear out the battery cover and it would become loose over time.
I think it’s safe to conclude that having easy – i.e. inexpensive – access to multiple phone lines in Uganda is beneficial to people living there for the reasons that I’ve explained. People who are deriving statistics on mobile phone usage in Uganda should be aware of the regular practice of having multiple phone lines as mobile phone penetration rates would be inflated if statistics are derived solely from customer numbers provided by mobile network operators.
Update: For a more general and academic view of mobile phone use developing countries, check out this post by Richard Heeks.
