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Reasons why the calls drop

When we had landline phones, our calls wouldn’t drop if we could get through, but it used to go to wrong numbers several times. Despite being a wired connection, the landline calls went to many undesired receivers, creating quite a lot of stress and embarrassment. It would take hours to fetch a trunk call. It’s with the wireless cellular phones, we don’t have to wait for hours to make a call, but many a times, the call drops. The users have been complaining about it for a long long time and recently, a government minister had raised the issue of dropped calls during his parliament plenary.

Having said this, we all acknowledge that missing a call on our cellular phones is indeed a public concern and the people may want to know about why the calls actually drop.

Let’s, first, have a look how does a call flow. When a caller types a number on his or her cellphone, the call has to travel through at least 40 nodes before it reaches the receiver. This is how the technology works. When a call goes out of a BTS, it has to go through ICX, IGW, IIG and some fibre operators. A wireless call is very much susceptible to get dropped when it has to cross 40 thresholds.

The authorities have a regulation in place that a mobile phone operator has to distribute its calls among all the licensed IIGs, ICXs, IGWs etc. However, sometimes those gateways fail to pay their dues and the authorities abruptly shut them down. Now, what would the operator do? Recently, the authorities had shut down four such gateways and the operators had to divert their traffic to others. And they could take the load and, perhaps, a million calls had dropped.

Everyone blamed the operator.

Problems in an operator’s internal gateways such as Base Station Controller, Mobile Switching Centre etc., can also cause call drops.

The shortage of spectrum is also an issue when it comes to call drops. The operators cannot afford to buy more spectrum as their return on investment won’t match with the exceptionally high fees that the authorities charge. It’s worthwhile to mention that right at the moment, about 185 megahertz of spectrum is lying unused. The authorities couldn’t sell them. The operators have been requesting the authorities for revisiting the price of spectrum which is one of the highest in the world.

The density of population could be another reason for a call to drop, no matter how strong the radio signal is. One BTS has a certain capacity for handling a certain number of calls. When a BTS gets overburdened due to too many calls, many won’t certainly go through. Take a cricket match in a stadium, for example. If we say that there are about four to five BTSs nearby and with the presence of 35,000 users in one single spot, they are bound to fail; don’t they? And if we take Dhaka’s Banasree, for example, it’s a Herculean task to reach to every person in that area. The owners of the buildings aren’t agreeing to provide spaces to the operators for setting up the towers.

There are hundreds like Banasree. And despite that problem, everyone blames the operators.

Then, sudden erection of a building can also cause a problem. The radio wave that you used to receive all this time is suddenly intercepted by a new building, creating havoc to your phone calls and data signals.

There are, of course, coverage gaps. Every inch of the landmass cannot be covered due to the sheer lack of the operators’ inability of construct towers across the country. There are several obstacles. The operators, even with the help of the tower companies, don’t get enough space for erecting a tower.

Take Dhaka’s Shahbagh, DOHS, Bailey Road, cantonment and border areas, for example. The operators are prohibited to place a BTS in order to reach to the people. Take a few areas where security is a priority and jammers are used. The use of jammers that would lead to a call drop or a call might get muted.

The towers containing BTSs require steady flow of electricity. Now, Bangladesh isn’t a landmass to have to a 24-hour power flow across the country. Come rains, come squally wind – the power flow is stopped or rationed across the country. The operators’ power generators live up to their steam and the batteries die down.

It’s exactly at that time, the call is bound to drop.

The cosmos of fibre is controlled by the NTTNs where the operators absolutely don’t have anything to do. They have to depend on the licensed fibre operators whose responsibility is to lay and maintain the fibre. When the fibre is cut due to hundreds of construction work, the call is bound to drop. Moreover, the fibre licensees control the speed; and no matter how much speed an operator seeks, it gets exactly what the fibre company offers. The operators don’t have any other choice but to stick to the same fibre company. They don’t have any other choice.

It must also be mentioned here that call drop is a quality-of-service issue. The mobile phone operators have their guidelines for QoS, but other operators in the ecosystem don’t. We should also keep this aspect in mind while we work for reducing the number of call drops; we should also think of a set of guidelines of QoS for other operators.

Our handsets could also be another reason for call drops. The strength of receiving calls isn’t the same for all types of handsets. Malfunction of handsets might also lead to call drop.

The reasons of call drops are many and it won’t be much fair if we keep blaming only the mobile operators for this. The industry average for call drops is about 0.8 per cent, which is lower than the average of the developed world and within the ceiling of the telecom regulator.


First published in Dhaka Tribune on 10 November 2018.

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