Internet Bandwidth consumed in making VoIP calls

This one is bit technical. As many of us have started making voice calls on the IP in our smartphones, I thought many of you would be interested to know how much internet bandwidth is consumed if you make a one minute of Voive call on IP i.e. VoIP call. Caveat - Some of highly technical stuff required cross-authentication from Geeks  (Learnt this from Wiki)

Here you go.....

Number of Bytes Consumed in VOIP

To know exactly how many bytes a voice conversation consumes, one needs to know which codec her VoIP service is using. 

CODECS 

A codec is a compression engine that transforms your (analog) voice into digital data, removing the silent moments (which make up to half of all conversations), and do other things to render the data load as light as possible. A codec is an algorithm (sort of a computer program), most of the time installed as a software on a server or embedded within a piece of hardware (IP Phones), that is used to convert voice (in the case of VoIP) signals into digital data to be transmitted over the Internet or any network during a VoIP call.

The word codec comes from the composed words coder-decoder or compressor-decompressor. Codecs normally achieve the following three tasks :

• Encoding – decoding
• Compression – decompression
• Encryption - Decryption

Encoding - decoding

Codec digitizes your analog voice to digital. When you talk over normal landline phone, your voice is transported in an analog way. But with VoIP, your voice is converted into digital signals. This conversion is technically called encoding, and is achieved by a codec. At destination, digitized voice is to be decoded back to its original analog state so that the other person can hear and understand it.

Compression – decompression

Bandwidth is a scarce commodity. To make the digitized voice less bulky, it is compressed. By compression, the same data is stored but using lesser space (digital bits). Once it reaches its destination, it is decompressed back to it original state before being decoded. 

Encryption – decryption

Encryption is one of the best tools for achieving security. It is the process of changing data into such a state that it no one can understand. This way, even if the encrypted data is intercepted by unauthorized people, the data still remains confidential. Once the encrypted data reaches destination, it is decrypted back to its original form. Often, when data is compressed, it already is encrypted to a certain extent, since it is altered from its original state.

Common VoIP Codecs

Codec	Bandwidth/kbps	Comments
G.711	64	Delivers precise speech transmission. low processor requirements. Needs at least 128 kbps for two-way.
G.722	48/56/64	Adapts to varying compressions
G.723.1	5.3/6.3	High compression with high quality audio.  Lot of processor power.
G.726	16/24/32/40	An improved version of G.721 and G.723 (different from G.723.1)
G.729	8	Excellent bandwidth utilization. Error tolerant. License required.
GSM	13	High compression ratio. Free and available in many hardware and software platforms.
iLBC	15	Robust to packet loss. Free
Speex	2.15 / 44	Minimizes bandwidth usage by using variable bit rate.

The approximate values for data consumption of the most common codecs used for VoIP are as follows:

Codec      BR                     NEB

G.711      64 Kbps      87.2 Kbps

G.729      8 Kbps        31.2 Kbps

G.723.1   6.4 Kbps      21.9 Kbps

G.723.1   5.3 Kbps      20.8 Kbps

G.726      32 Kbps      55.2 Kbps

G.726      24 Kbps      47.2 Kbps

G.728      16 Kbps      31.5 Kbps

iLBC         15 Kbps      27.7 Kbps

BR = Bit rate
NEB = Nominal Ethernet Bandwidth (one direction)

Note  - The G.729 codec is one of the best performing voice codecs and most good VoIP services use it.

Calculation of Bandwidth required

Example - for one minute of talk with the G.729 codec.

Now G.729 uses 8kpbs of sampling. Normally one packet of 20 Bytes is sent. With a sampling rate of 8kpbs this means that in one sec, 50 packets are to be sent.

If we are using frame relay protocol over ethernet, the overheads to be used are as follows - 

Frame relay - 6 Bytes(incl header and trailer)

RTP - 40 bytes (breakup 20 bytes of IP, RTP-12 & UDP - 8) [Note if cRTP is used these 40 Bytes can be converted into 4 Bytes]

Ethernet - 18 bytes

Therefore, for each packet of 20 bytes in this case 64 Bytes of protocol and other header bytes are added. Therefore total 84 Bytes will be send. Overall 50 such packets are semt per sec, therefore bit rate is 50*84*8= 33.6 kbps (Mentioned as ~32 kpbs)

This translates into 1920 kilobits (60 x 32) in one minute, which in turn is 240 kilobytes (KB) per minute (1 byte is 8 bits). Now that’s only for the data going out. Inbound data (which also counts) takes the same load, so one can double the figure to 480 KB. This gives a round value to 0.5 MB per minute of conversation.

However, there are many parameters, that are rather technical in nature, affecting the values above. Among them are the compression technology, the size (payload) of the voice packets, the intervals at which they are sent, packet overhead, network protocol used and whether silence suppression is used. (Pl refer table below). If silence suppression/voice activity detection is used, the bandwidth consumption may drop 50%

Packet voice transmission requirements (Bits per second per voice channel)
Codec	Voice bit rate	Sample time	Voice payload	Packets per second	Ethernet	PPP or Frame Relay RTP cRTP
G.711	64 Kbps	20 msec	160 bytes	50	87.2 Kbps	82.4 Kbps	68.0 Kbps
G.711	64 Kbps	30 msec	240 bytes	33.3	79.4 Kbps	76.2 Kbps	66.6 Kbps
G.711	64 Kbps	40 msec	320 bytes	25	75.6 Kbps	73.2 Kbps	66.0 Kbps
G.729A	8 Kbps	20 msec	20 bytes	50	31.2 Kbps	26.4 Kbps	12.0 Kbps
G.729A	8 Kbps	30 msec	30 bytes	33.3	23.4 Kbps	20.2 Kbps	10.7 Kbps
G.729A	8 Kbps	40 msec	40 bytes	25	19.6 Kbps	17.2 Kbps	10.0 Kbps
Note: RTP assumes 40-octets RTP/UDP/IP overhead per packet Compressed RTP (cRTP) assumes 4-octets RTP/UDP/IP overhead per packet Ethernet overhead adds 18-octets per packet PPP/Frame Relay overhead adds 6-octets per packet

If we take the value of 50 kbps for any codec, it will give (after calculations and approximations) 0.75 MB per minute of conversation.

US regulator rejects proposal for free wireless broadband service - Interesting!!

Federal regulators (FCC- Federal Communications Commission)have shot down a proposal by a startup called M2Z Networks Inc. to build a free, nationwide wireless broadband network using a spare slice of airwaves.  M2Z had requested that the winner of an auction for the radio spectrum would provide free Internet service to anyone who connects to it.  M2Z's business model was - offering free basic wireless broadband access — with speeds of up to 768 kilobits per second — that would be supported by advertising in addition to a faster, premium service.

The FCC is still studying possible uses of the spectrum.

3G bidding - Is this the third & Last round of telco competition in India?

The DoT (Department of Telecom) will release a detailed information memorandum (IM) this week on the upcoming 3G auctions. As reported by economic times, the IM (information memorandum) to be released is likely to contains details regarding the billing schedule, qualifications of bidders, terms and conditions, payment schedules and other technical and commercial specifications that are critical to enable bidders to plan their auction strategy.

The DoT clarified that global telecom operators who do not operate in India are welcome to participate, though they will have to acquire a Unified Access Service Licence (UASL) to be eligible to bid. This implies some uncertainty for potential foreign bidders. At present, a pan-India UASL costs Rs 1,658 crore and comes bundled with 4.4 MHz of 2G spectrum. However, recent proposals to unbundle the licence from spectrum and to change its cost are still pending and could remain unresolved at the time India conducts its 3G auctions. This change is owing to a severe 2G spectrum crunch being faced in India with over 300 applicants waiting in queue for 24 months or more to get new spectrum/licences. DoT officials believe that global operators will be willing to join this queue, but given the fact that there is a shortage, the uncertainties relating to the cost and 2G spectrum availability may prove to be a deterrent. Any proposal to change the terms and conditions of licence has to be referred to the Trai and this usually involves a detailed process, including several consultations and Open House sessions with all stakeholders.

Domestic operators Bharti, Vodafone, Reliance, Tatas and Idea are expected to be the main players in the 3G auction ring. Nordic telecom giant Telenor, which recently secured 67% equity in Unitech Wireless is reported not to opt for a pan-India 3G licence but bid for a select few 3G circles. Aircel, Loop, Swan and Datacom may also place bids in some strategic circles.

The reserve price for pan-India 3G spectrum is pegged at Rs 3,500 crore. It is believed that given the limited number of slots, the government may be able to receive a price in the range of Rs 6,000 crore plus for each of the slots giving an additional revenue of Rs 25,000 crore to the exchequer for the current fiscal. The auction of third generation spectrum or airwaves, is likely to start this November. The EGoM has recently approved placing four slots of 5 MHz each in the 2.1 GHz band for auctions in 3G. If the auction is held in December as scheduled, it is highly likely that India will see four new 3G operators before the end of 2010.

To me this seems to be last round of competition between telcos in India. What I foresee is that after aggressive bidding for 3G licences, some of the operators will make huge losses. Then the consolidation phase will follow. By 2012 some of the players will start handling the batten - not to new players but to the one running in adjacent lanes.

Mobile Number Portability (MNP) to kick in from 31st Dec in India

Mobile number portability (MNP) — a facility that allows customers to switch operators but retain their numbers — will kick in from December 31 across the metros and category A circles, such as Tamil Nadu and Karnataka, while the rest of the country will have access to the facility from March 31, 2010.

TRAI, the telecom regulator in India, also issued a slew of guidelines for MNP implementation. - As per the norms, once a user switches operator, he must stay for at least three months (90 days) with the new service provider before moving to another operator.
- Besides, a user holding a mobile connection is eligible to make a porting request only after three months of the date of activation of his number.
- The subscribers, who wish to port their numbers must submit their requests in writing to their service providers. The new operator must mandatorily carry out all checks, including identity verification, before completing the process, the regulator said, adding that the entire process must be completed within four days.
- Pre-paid users must give an undertaking of being aware that balances on both talktime and minutes will not be carried over to the new operator they are switching to. Post-paid customers must furnish proof that all outstanding dues to their current operator have been cleared, TRAI added.
- The operators must inform the customer about the exact date and time for the process. The regulator has also made it clear that while the operator is porting the number, the customer may have to face a ‘no service period’ that can be extended for up to a few hours during which they will not be able to receive and make calls. But in a bid to address these concerns, TRAI has said the new operator must provide the customer with a list of missed calls and messages sent during the ‘no service period’.

Syniverse Technologies and MNP Interconnection Teleco Solutions, the two companies chosen to implement it in India, had projected to regulator that less than 3% of the country’s expected 550 million-plus mobile users will go in for MNP by 2010. The regulator, when issuing MNP norms, however, did not specify the charges that customers will have to pay for switching their operator. Syniverse and MNP Interconnection had proposed to charge customers between Rs 75 and Rs 200 for porting an operator, but the regulator is yet to take a final call on the pricing issue.

Its penalty time for Indian Telcos - DoT slaps Rs 32 cr of penalty for failing to adhere to sunscriber verification norms

Government has slapped a penalty of Rs 32 crore on mobile operators for failing to adhere to the subscriber verification norms in 2008-09. The penalty has been on all the mobile operators, including BSNL and MTNL, for failing to meet the subscriber verification condition. With a penalty of Rs 1,000 for each unverified subscriber, the number of such users comes to about 3.2 lakh.

Earlier in April this year, DoT introduced a graded penalty system under which operators pay Rs 50,000 per subscriber if more than 20 per cent of their user base is without valid identity documents. However,the penalty continues to be Rs 1,000 per user if the mobile operator's unverified subscriber base is less than 5 per cent of its user base in each of the circles.

With the customer base swelling at ~ 15 million per month, I bet, if strictly implemented, this can bring in about Rs 2000 to Rs 3000 million of revenues per year.

Rollout penalty for Indian Telcos - Delayed but not denied

The government of India has proposed a penalty of Rs 135.60 crore on private telecom operators, including Tatas, Airtel and Reliance Communication, for delays in rolling out networks. Though, the department of telecom (DoT) has lowered the total quantum of penalty from Rs 477 crore decided earlier to Rs 135.60 crore after repeated representations by the operators, giving a major benefit to all big private telecom players. Almost all private players except Vodafone-Essar face penalties.

As reported in Economic times, the penalty comes to over Rs 41 crore on Tatas, Rs 31 crore on Airtel and Rs 19.65 crore on RCOM. Among others, Aircel faces a penalty of Rs 28.85 crore, HFCL has a liquidated damages of Rs 7 crore and the two PSUs — BSNL and MTNL, along with Vodafone-Essar face no penalty.

The cases for imposition of liquidated damages were processed since 2005 and show-cause notices for imposition of liquidated damages (amounting to Rs 477.15 crore) were issued in 96 cases to 10 operators. There were representations from industry pointing out delays in statutory clearances, grant of spectrum for access, among other factors, for delayed rollouts. Thus, it was decided to revisit the subject and DoT has arrived at revised lower penalty for these operators.

As suggested in one of my earlier posts its also time to adopt Swedish model for penalizing operators for not meeting roll out obligations and are in turn hoarding spectrum. (For reading the full post click here)

Radio Spectrum fee -Lessons from Sweden

­The Swedish Post and Telecom Agency (PTS) has announced that it will gradually implement a new model for spectrum charges starting from next year that will penalise license holders who have not maximised the use of their radio spectrum. In general, it could be said that the new model means that licence holders with a large holding of spectrum and with no rollout, or a low degree of rollout, will be imposed higher charges. Licence holders with a high degree of rollout and a small holding of spectrum will have lower charges. Licence holders will have to pay more for spectrum in low frequency bands. However, the total charges imposed by PTS for the area of radio will not increase.

The new model for charges is technology-neutral and will be implemented gradually over the course of several years for various types of licence. The first category in line for implementation is block and television licences in 2010. RTTE fees will also be changed for block and television licences.

In The new model, Licence holders will find it easy to anticipate future annual charges, which will for example benefit the second-hand market.