If you make a lot of phone calls while on the road, then Vodafone is the best mobile operator for you in Delhi, according to the results of a two-day ‘drive test’ conducted by quality auditing firm TUV SUD on behalf of the Telecom Regulatory Authority of India.
The drive test, which involved making around 450 calls per operator while driving over a distance of 300 km, also showed that Reliance GSM scored very poorly in terms of network quality.
Bharti Airtel, the market leader in Delhi, seemed to be struggling more with quality issues compared to rival Vodafone.
It must be noted that these results are applicable only for on-road coverage. When it comes to in-building coverage, the numbers are likely to favor Bharti Airtel and Vodafone, both of which have 2G services running on 900 Mhz spectrum. Idea also has 900 Mhz spectrum, but that has been diverted to 3G services.
The drive test was conducted using a computer connected to several mobile phones. Each mobile phone had a SIM card from a different operator. At the same time, each mobile phone was made to dial given phone numbers and calls were connected and checked for quality.
The drive test checked for five different parameters – signal availability (coverage), call success (availability), call continuity (retainability), mobility and voice quality.
CALL DROPS
As most Delhiites would know, the most crucial element in all these is call continuity or the ability of the network to continue a call without dropping it.
On this criterion, Tata DoCoMo CDMA (there is no Tata GSM in Delhi) came out on top overall and Idea came out on top among GSM operators. However, before congratulating Idea for its excellent call drop statistics, you should remember that call drops can be measured only if the call goes through.
In other words, if the call is not allowed in at all (or blocked due to congestion), there is no point in talking about low call drops. This point is relevant in evaluating Tata CDMA and Idea’s call drops, and is further explained in the next section.
Besides the above two, Vodafone and Aircel had decent call sustainability rates of around 95%. In other words, call drops were only 1 in 20.
The market leader, Bharti Airtel (which has the biggest mobile network in Delhi) had a call drop rate of 8%, and managed to sustain only 92% of the calls for 90-120 seconds. As a result, what Bharti offered in terms of better coverage, it took away in terms of call drops.
The highest call drop rate was for Reliance Communications’ GSM network. It had a call drop rate of 17.3%, meaning that nearly one in five calls could not be completed.
The test calls were made for 1.5-2.0 minutes each.
CALL CONNECT RATE & COVERAGE
The second biggest problem faced by mobile subscribers is connectivity. Lack of connectivity can be because of two factors — lack of coverage (which was studied separately) and network congestion, which was studied separately.
Whether or not a call goes through is therefore dependent on whether coverage is there, and whether congestion is there or not.
In some cases, coverage was there, but because of high congestion, the coverage turned out to be quite useless.
This is the case with Idea Cellular, which had average network availability, but poor call success rate (call acceptance).
For example, both Vodafone and Idea had the same network coverage rate of 87%, and therefore were well above everyone else in coverage. The worst coverage rate was Reliance GSM and Tata DoCoMo. Both had signals only at around 58% of the tested spots.
Not surprisingly, the market leader – Bharti Airtel, had the highest reach. Against 87% for Vodafone and Idea, Bharti Airtel had network presence in 91.3% of all the test spots. However, as we observed earlier, Bharti Airtel had a notably higher level of call drops compared to Vodafone.
Now, we move from coverage and signal to call success (which usually depends on how congested the network is.)
It is useless to have a signal if your call is blocked.
Here is where Idea Cellular really takes a beating, and Vodafone shines again. Though both have the same network coverage of 87%, Vodafone offers a success rate of 95.3%, while Idea gives a success rate of just 73.9%. In other words, nearly 1 in every 4 calls made on Idea network on Delhi roads don’t go through even if the signal is there.
The best record in this matter belongs to Tata DoCoMo CDMA. However, we have seen that Tata DoCoMo CDMA signals were present only in 58% of the tested spots.
The market leader, Bharti Airtel, had a call success rate of 91.8%, implying that almost 1 in 10 attempts at dialling a number was futile.
Aircel also had good success ratio (97.1%), but its signal was available on in 74% of the tested spots.
CALL QUALITY
The next factor to be checked to determine the best mobile network in Delhi was voice quality. This is determined largely by congestion, signal strength and lack of interference.
In this case, only Tata DoCoMo CDMA managed to meet TRAI’s guideline on voice quality.
The worst offenders in terms of quality of connection were Airtel, Aircel (82.69%) and Reliance (85.36%). Airtel’s poor connection quality (84.32%) can probably be attributed to the high number of subscribers supported by the network.
Among GSM players, the operator with the best connection quality were Vodafone and Idea, with around 91% of the calls being of acceptable quality.
INTERFERENCE
The agency also tested a factor known as interference. Basically, in congested places, one tower of Vodafone will be located only a few hundred meters from another tower. As a result, signals from these towers may sometimes interfere with each other.
This is particularly a problem when there are large numbers of towers. Vodafone, for example, has 6115 towers in Delhi and Airtel has 5988. Idea has 4804 towers. Reliance has 2494 GSM towers, while Aircel has 3749 towers.
Carrier interference turned out to be a bigger problem in Delhi compared to the more congested Mumbai.
The highest level of interference was found in Airtel and the lowest in Tata CDMA. Among GSM players, the lowest interference was in Idea and Vodafone’s network.
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