Circular 19/2022/TT-BTTTT National technical regulation on quality of telephone service on Public Land Mobile Network

          CIRCULAR

On issuance of National technical regulation on quality of telephone service on the Public Land Mobile Network

Pursuant to the Law on Standards and Technical Regulations dated June 29, 2006;

Pursuant to the Telecommunications Law dated November 23, 2009;

Pursuant to the Law on Radio Frequency dated November 23, 2009;

Pursuant to Decree No. 127/2007/ND-CP dated August 1, 2007 of the Government detailing and guiding the implementation of a number of articles of the Law on Standards and Technical Regulations;

Pursuant to Decree No. 78/2018/ND-CP dated May 16, 2018 of the Government amending and supplementing a number of articles of Decree No. 127/2007/ND-CP dated August 1, 2007 of the Government detailing the implementation of a number of articles of the Law on Standards and Technical Regulations;

Pursuant to Decree No. 48/2022/ND-CP dated July 26, 2022 of the Government regulating the functions, tasks, powers and organizational structure of the Ministry of Information and Communications;

At the request of the Director of the Department of Science and Technology,

The Minister of Information and Communications promulgates a Circular issuing national technical regulation on quality of telephone service on the Public Land Mobile Network.

          Article 1. Issued together with this Circular is the National Technical Regulation on quality of telephone service on the Public Land Mobile Network (QCVN 36:2022/BTTTT).

Article 2. Effect

1. This Circular takes effect from July 1^st, 2023.

2. Circular No. 40/2015/TT-BTTTT dated December 25, 2015 of the Minister of Information and Communications promulgating "National technical regulations on quality of telephone services on terrestrial mobile telecommunications networks" ends its effect from July 1, 2023.

Article 3. Chief of Office, Director of the Department of Science and Technology, Heads of agencies and units under the Ministry of Information and Communications, Directors of Departments of Information and Communications of provinces and central cities and organizations, relevant individuals are responsible for implementing this Circular./ .

Preface

QCVN 36:2022/BTTTT replaces QCVN 36:2015/BTTTT.

QCVN 36/2022/BTTTT was compiled by the Authority of Telecommunications, evaluated by the Ministry of Science and Technology, approved by the Department of Science and Construction, and issued by the Ministry of Information and Communications together with Circular No. 19/2022/TT-BTTTT dated November, 29, 2022.

NATIONAL TECHNICAL REGULATION

ON QUALITY OF TELEPHONE SERVICE

ON THE PUBLIC LAND MOBILE NETWORK

1. GENERAL RULES

1.1. Scope

This regulation stipulates the limits of quality criteria ­for telephone services on public land mobile networks.

1.2. Applicable subjects

This regulation applies to telecommunications enterprises providing telephone services on public land mobile networks (hereinafter referred to as DNCCDV) that manage the quality of this service according to State and the Ministry of Information and Communications’ regulations.

This standard is also the basis for users to monitor the quality of telephone services on public land mobile networks of businesses.

1.3. References

ITU-T P.863 (March 2018): “Perceptual Objective Listening Quality Assessment”.

ITU-T P.800 (August 1996): “Methods for subjective determination of transmission quality”.

1.4. Explanation of words

1.4.1. Customers (service users)

Vietnamese or foreign individuals and organizations use telephone services on the public land mobile network provided by DNCCDV.

1.4.2. Service quality

The combined results of the indicators show the level of satisfaction of service users with that service.

1.4.3. Service provision areas

The geographical area in which the service provider announces the ability to use telephone services on the public land mobile networks according to the quality level specified in 2.1 of this regulation. Service provision areas include:

- Areas providing GSM/WCDMA telephone services on the public land mobile network (hereinafter referred to as GSM/WCDMA area);

- Areas providing VoLTE phone services on the public land mobile network (hereinafter referred to as LTE area).

1.4.4. Minimum received signal level

The minimum power level obtained in the service area. Minimum received signal level of:

- GSM/WCDMA area is: -100 dBm;

- LTE zone is: -121 dBm.

1.4.5. Call

- A call in the GSM/WCDMA area is a call that is established, maintained, and released on the GSM/WCDMA network and a call that during the setup process, the subscriber transfers from the LTE network to the GSM/WCDMA network;

- A call in the LTE area is a call established, maintained and released on the LTE network;

- A call between the GSM/WCDMA area and the LTE area is a call in which the calling subscriber and the called subscriber are established, maintained and released at the same time on the GSM/WCDMA and LTE networks.

1.4.6. Problem

Damages to one or more elements of the public land mobile network affecting cells in the land mobile communication network, leading to partial or complete interruption of telephone service provision.

1.4.7. Cells

A radio frequency coverage area of a land mobile communication station.

1.4.8. Mobile broadcasting station

An element of the land mobile network responsible for connecting communications with subscribers.

1.4.9. Call setup succeed

A call in which, after dialing, the calling subscriber receives a response signal correctly return the status of the called subscriber, including:

- There is a ring response or busy signal from the called subscriber;

- There is a sound signal from the network about the status of the called subscriber (blocked incoming call, cannot be contacted).

1.4.10. Call setup failed

A call where, after dialing, the calling subscriber does not receive a response signal Correctly returns the status of the called subscriber

1.4.11. Call dropped

The call was successfully established but was lost midway through the conversation due to the public land mobile network.

1.4.12. Determination method:

Determination methods are methods of assessing service quality with a prescribed minimum sampling level, that State management agencies and service enterprises apply in measuring and testing service quality.

Each quality indicator is prescribed one or more different determination methods. If service quality indicators are determined by many different methods specified in this Regulation, the quality indicators are considered appropriate when the evaluation results by each method are consistent with the indicator prescribed criteria.

1.5. Abbreviation

2. TECHNICAL REGULATIONS

2.1. Technical quality criteria

2.1.1. Radio network availability

2.1.1.1. Definition

The readiness of the radio network is the ratio (%) between the number of measurement samples with a received signal level greater than or equal to the minimum received signal level specified in 1.4.4 to the total number of measurement samples.

2.1.1.2. Target

Radio network availability ≥ 95 %.

2.1.1.3. Determining methods

Simulation method: The minimum number of measurement samples is 100,000 samples for mobile outdoor measurements at different hours of the day, in the service area. For service providers with 2 service areas, the minimum number of measurement samples in each area is 50,000.

2.1.2. Percentage of failed setup calls

2.1.2.1. Definition

The failed setup call rate is the ratio (%) of the number of failed setup calls to the total number of calls.

2.1.2.2. Target

Percentage of failed setup calls £ 2 %.

2.1.2.3. Determining methods

Determination can apply either or a combination of the following two methods:

- Call simulation: Minimum number of simulated calls is 3,000 calls, distributed according to test conditions: indoor measurement (minimum 1,000 calls); outdoor measurements at fixed locations (minimum 1000 times); Mobile outdoor measurement (minimum 1,000 calls). For service providers with 2 service areas, the distribution of simulated calls is as shown in Table 1. For each test condition, measurements are performed at different hours of the day, in the service area; The time interval between two consecutive simulated calls originating from the same calling subscriber is not less than 30s. Requirements for test locations are specified in Appendix A.

Table 1 – Minimum number of calls

- Monitoring using available network features: The minimum number of calls sampled is all calls for 7 consecutive days.

2.1.3. Dropped call rate

2.1.3.1. Definition

Dropped call rate is the ratio (%) of dropped calls to the total number of successfully established calls.

2.1.3.2. Target

Dropped call rate £ 2 %.

2.1.3.3. Determining methods

Determination can apply either or a combination of the following two methods:

- Call simulation: Minimum number of simulated calls is 3,000 calls, distributed according to test conditions: indoor measurement (minimum 1,000 calls); outdoor measurements at fixed locations (minimum 1000 times); Portable outdoor measurement (minimum 1 000 calls). For service providers with 2 service areas, the number of simulated calls is distributed as Table 1. For each test condition, measurements are performed at different hours of the day, in the service area; Simulated call length ranges from 60s to 180s; The number of simulated calls with a length of 60s to 90s must ensure at least 50% of the total number of simulated calls; The time interval between two consecutive simulated calls originating from the same calling subscriber is not less than 30s. Requirements for test locations are specified in Appendix A.

- Monitoring using available network features: The minimum number of calls sampled is all calls for 7 consecutive days.

2.1.4. Voice quality

2.1.4.1. Definition

Voice quality is an integrated index of the quality of voice transmission on a voice channel determined by calculating an average score with a MOS scale from 1 to 5 according to ITU Recommendation P.800.

2.1.4.2. Target

Average phone service quality must be ≥ 3.5 points.

2.1.4.3. Determining methods

Simulation measurement method. Measurement method is carried out according to ITU-T Recommendation P.863. The minimum number of simulated calls is 3,000 calls, distributed under 3 testing conditions: indoor measurement (minimum 1,000 calls); outdoor measurements at fixed locations (minimum 1 000 times); Portable outdoor measurement (minimum 1 000 calls). For service providers with 2 service areas, the number of simulated calls is distributed as Table 1. For each test condition, measurements are performed at different hours of the day, in the service area; The time interval between two consecutive simulated calls originating from the same calling subscriber is not less than 30s. Requirements for test locations are specified in Appendix A.

2.1.5. Charge recording accuracy

2.1.5.1. Percentage of calls incorrectly billed

2.1.5.1.1. Definition

The rate of misbilled calls is the ratio of the number of misbilled calls to the total number of calls.

Calls that are incorrectly billed include:

- The call is recorded but not real;

- The call is real but not billed;

- Incorrectly recorded caller numbers and/or called numbers;

- The call where the absolute value of the difference between the recorded call length and the actual conversation length is greater than 1s;

- The billed call has a start time that differs by more than 9s in absolute value compared to the actual time taken according to the national standard clock.

2.1.5.1.2. Target

The rate of incorrectly billed calls is £0.1%.

2.1.5.1.3. Determining methods

The total number of sampled calls required is a minimum of 10,000 calls. Determination can apply either or a combination of the following two methods:

- Call simulation: Perform simulations at different hours of the day, within the service area and in intra-network and inter-network directions. The interval between two consecutive simulated calls originating from the same calling subscriber is not less than 10s. The number of simulated calls with a length from 1s to 90s is at least 60% of the total number of simulated calls.

- Beacon monitoring: Sampling calls at different hours of the day. The signal monitoring machine connection point at the switchboards and performs on the signal flows for normal daily operations of the terrestrial mobile telecommunications network and ensures that it does not affect the normal operation of the network.

2.1.5.2. Percentage of talk time recorded incorrectly

2.1.5.2.1. Definition

The rate of misbilled talk time is the ratio of the total absolute value of misrecorded time of misbilled calls to the total time of the calls.

2.1.5.2.2. Target

The rate of incorrect recording of talk time is £0.1%.

2.1.5.2.3. Determining methods

The determination method is similar to the indicator Ratio of incorrectly billed calls (see 2.1.5.1.3).

2.1.6. Percentage of calls that are charged and billed incorrectly

2.1.6.1. Percentage of calls incorrectly billed

2.1.6.1.1. Definition

The rate of incorrectly billed calls is the ratio of the number of incorrectly billed calls to the total number of calls.

Incorrectly billed calls include:

- The call is not included in the billing data but is charged;

- The call is included in the billing data but is not charged;

- The call has the wrong caller number and/or called number compared to the billing data;

- The call has wrong start time and/or end time and/or conversation length compared to the billing data;

- The call with charge is calculated incorrectly.

2.1.6.1.2. Target

The rate of incorrectly charged calls is £0.01%.

2.1.6.1.3. Determining methods

Compare at least 10,000 billed calls with billing data.

2.1.6.2. Percentage of calls that are incorrectly billed

2.1.6.2.1. Definition

The incorrectly billed calls rate is the ratio of the number of misbilled calls to the total number of calls.

Incorrectly billed calls include:

- Calls included in billing data but not billed;

- The call is not included in the billing data but is included in the invoice;

- The call has the wrong caller number and/or called number compared to the billing data;

- Incorrect call start and/or end time and/or conversation length compared to billing data;

- Calls where the charge on the invoice is recorded incorrectly compared to the charge data.

2.1.6.2.2. Target

The rate of incorrectly billed calls is £0.01%.

2.1.6.2.3. Determining methods

Compare at least 10,000 billed calls with billing data.

2.2. Service quality indicators

2.2.1. Service availability

2.2.1.1. Definition

Service availability (D) is the proportion of time during which the network is available to provide service to customers.

                 In which: T_r : Time to determine service availability;

N: Total number of failures during the availability determination period;

R_i : Total number of cells at the time of the i^th incident;

r_i : Number of cells affected in incident i^th ;

t _i : I^th incident time.

2.2.1.2. Target

Service availability D ³99 %.

2.2.1.3. Determination method

Statistics of all incidents during the availability determination period. The minimum availability determination period is 3 consecutive months.

2.2.2. Customer complaints about service quality

2.2.2.1. Definition

Customer complaints about service quality are customer dissatisfaction with service quality reported to the service provider in writing.

2.2.2.2. Target

The customer complaint rate about service quality is £0.25 complaints/100 customers/3 months.

2.2.2.3. Determining methods

Statistics on all customer complaints about service quality for a minimum period of 3 consecutive months.

2.2.3. Respond to customer complaints

2.2.3.1. Definition

A response to a customer's complaint is a document from the service provider notifying the customer with a written complaint about the receipt and consideration of resolving the complaint.

2.2.3.2. Target

DNCCDV must have a written response to 100% of customer complaints within 2 working days from the time of receipt of the complaint.

2.2.3.3. Determining methods

Statistics on all written responses to customer complaints about service quality for a minimum period of 3 consecutive months.

2.2.4. Customer service

2.2.4.1. Definition

The customer support service is a service that answers questions, advises, guides users, receives requests, and provides relevant information to customers about telephone services on the mobile land telecommunications network.

2.2.4.2. Target

- Time to provide customer support services via phone is 24 hours a day.

- The rate of calls to the customer support service successfully accessing the circuit, sending a connection request to the operator and receiving a response from the operator within 60 s ≥ 80%.

2.2.4.3. Determining methods

Determination can apply either or a combination of the following two methods:

- Simulate or call workers: Simulate or call workers to the customer support service, the minimum number of test calls is 250 calls at different hours of the day.

- Monitoring by device or by available network features: The minimum number of calls sampled is all calls for 7 consecutive days.

3. MANAGEMENT REGULATIONS

3.1. Telephone services on public land mobile networks within the scope specified in 1.1 must comply with the provisions of this Regulation.

3.2. Measuring devices and measuring equipment: comply with the provisions of measurement laws.

4. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

4.1. Service providers must disclose to customers the service provision area in the form of a digital map. General requirements for service delivery areas in the form of digital maps are specified in Appendix B.

4.2. Service providers must ensure the quality of telephone services on public land mobile networks in accordance with this Regulation, declare service quality and submit to inspection by state management agencies. according to current regulations.

4.3. The specific responsibilities of service providers are specified in legal documents on telecommunications service quality management of the Ministry of Information and Communications.

5. IMPLEMENTATION ORGANIZATION

5.1. The Authority of Telecommunications and the Departments of Information and Communications are responsible for guiding and organizing the implementation of telephone service quality management on public land mobile networks according to this Regulation.

5.2. This regulation replaces QCVN 36:2015/BTTTT National Technical Regulation on quality of telephone services on terrestrial mobile telecommunications networks.

5.3. In case the regulations stated in this Regulation are changed, supplemented or replaced, the provisions in the new document shall comply.

5.4. During the implementation of this Regulation, if any problems or difficulties arise, relevant organizations and individuals should report in writing to the Ministry of Information and Communications (Department of Science and Technology) for be guided and resolved./.

 Appendix A

(Regulation)

Requirements for testing locations

Indoor measurement conditions: Measurement inside public works, such as airports, train stations, car stations, hospitals, museums...

Outdoor measurement conditions at fixed locations: Measurement at populated points such as surrounding areas: train stations, car stations, markets, hospitals, parks, cultural relics and scenic spots…

Mobile outdoor measurement conditions: Measurement during traffic on national highways, inter-provincial, inter-district roads, roads in populated areas...

Appendix B

(Regulation)

General requirements for Service Provision Area in the form of a digital map

Service provision areas in the form of digital maps are separate layers embedded on the online map platforms Google Maps, Bing Map, Esri...

Different Service Delivery Areas must be shown in different colors with a minimum resolution of 100 m x 100 m and clearly annotated.

The service provision area in the form of a digital map must have the ability to zoom in and out.

References

[1]             ITU E.804 (February 2014) “QoS Aspects for Popular Services in Mobile Networks”;

[2]             ITU E.804.1 (October 2020) “Application guide for Recommendation ITU-T E.804 on quality of service aspects for popular services in mobile networks”;

[3]             ITU-T G.1028 (June 2019) “End-to-end quality of service for voice over 4G mobile networks”;

[4]             Handbook for the Collection of Administrative Data on Telecommunications/ICT, the 2020 edition – ITU;

[5]             ETSI 102 250 (November 2019) Speech and multimedia Transmission Quality (STQ); QoS aspects for popular services in mobile networks;

[6]             ETSI TR 103 219 (April 2015) Speech and multimedia Transmission Quality (STQ); Quality of Service aspects of voice communication in an LTE environment;

[7]             GSMA IR 42 (July 2018) “Definition of Quality of Service parameters and their computation”;

[8]             QCVN 36: 2015/BTTTT “National technical regulations on quality of telephone services on terrestrial mobile telecommunications networks”.