Roaming technology - bridge of international networks

When traveling abroad but still want to communicate with a familiar mobile phone number, still browse e-mail in Outlook Express mailboxes in remote islands ., you can think of service. roaming is referred to as "roaming".

This is a general term in the telecommunications sector, indicating the extension of the connection service in a location other than the original registration place. This roaming occurs when a subscriber of a service provider (SP) uses another SP infrastructure. This second SP has no service or financial agreement with that subscriber in receiving and sending information that works with the first SP to support the user.

The object of roaming is mobile phone and Internet.

Roaming in mobile phone network

Source: Rentmobilephone In many cases, roaming occurs in the initial registration area of ​​the phone when it transmits information through another SP receiver tower - when the SP signal is initially too weak or the number of callers is too much.

In each different mobile phone network, roaming process will be different, but basically as follows:

- When the mobile device is turned on or transmitted via a handover station to the network, the network is "visited" this "see" the device and determines whether it is on the register list or not. and try to identify its "home" network. If the previous two networks did not have a "communication" agreement, the service could not be maintained and the guest network would refuse.

- In an acceptable situation, the network will contact the home network and request service information about its International Mobile Subscriber Identity (IMSI) device, in which the device is authorized. roaming or not.

- If successful, the guest network will begin to maintain a temporary subscription for the device. At the same time, the home network updates information to determine the device being managed on the server and the information sent to that device also ensures that it is transmitted correctly.

If there is a call to a roaming phone, the public phone network will direct it to the SP it registers. After that, this SP must direct it to the client network (service agreement). The guest network will provide a temporary internal phone number for the mobile phone. When this number is determined, the home network will forward the incoming call to the temporary number and forward it to the phone.

Types of roaming:

Roaming by geographical area

This roaming type is only capable of moving services from one area to another within the national border of a mobile operator. Initially, operators often restrict services in small areas (like a city). But later, with the development of GSM global mobile network technology and reduced cost, regional roaming is rarely implemented, except in countries with large geographical regions such as the US, Russia and India. . in which there are many network operators of each region.

In Vietnam, this is the case of products like Vinaphone and Mobifone in the area of ​​1,2,3 before. When calling local, inter-regional, regional, customers will be charged different rates. After that, these products charged according to a single region across the entire territory.

Geographic roaming of a network operator is also the form that EVN Telecom EVN is deploying with E-phone service. However, E-phone uses a fixed number but operates as a mobile network, which has been controversial and the company has to suspend roaming this way.

Roaming waves between providers

This type of roaming refers to the ability of a mobile operator to capture a broadcast area to a wave area of ​​another operator within the borders of a country. For example: Mobifone network subscribers are allowed to switch to Vinaphone when these two service providers have a roaming agreement with each other. This usually happens when a new company joins this field and needs a port compatible with the previous operator's infrastructure. They have to suggest that these operators allow roaming while taking the time to build their own network.

Currently, in Vietnam, roaming support networks are connected with Vinaphone and Mobifone on GSM technology. However, the Ministry of Post and Telematics has not yet allowed the above networks of VNPT to roam with CDMA networks, namely S-Fone and recently E-phone.

International Roaming

This service is capable of roaming to a network of foreign telecommunications service providers. This is a benefit for tourists and many people around the world. However, this type of problem may be problematic because countries have different bands, for example, most use the 900/1800 MHz band, while the US and some countries in the Americas use 850/1900 MHz band. . Therefore, when buying a phone to travel to different countries, you need to pay attention to choose the type of 3-4 frequency bands.

In Vietnam, the networks Vinaphone, Mobifone, Viettel and S-Fone have deployed international roaming services. Vinaphone has linked to 59 countries, Mobifone connected with 52 countries, Viettel registered to 43 countries and S-Fone also supported the network when you came to Korea, Taiwan, China and Japan.

These networks do not charge international roaming service fees but only charge for service usage. How to charge for calling, texting or receiving incoming calls, incoming messages are presented quite carefully on the website of Vinaphone , Mobifone , S-Fone . For Viettel's service, customers can ask support center.

When you want to use roaming service, customers must be postpaid subscribers and go to the centers to register. All charges will be recorded on the bill at the end of the month. Some networks may require single customers to deposit money in advance, and businesses such as businesses, VIP subscribers . will be exempt.

Roaming in the Internet

This form applies to registered accounts for Internet use. This is the ability to access the global network when away from home with only the local price or cheaper than the cost of long distance calls. For example, you have registered an Internet account of a service provider in Hanoi and travel to Hong Kong. Instead of paying for long-distance connections to Hanoi, you only need to pay connection fees in Hong Kong and a little money for roaming services.

Internet roaming is done when Internet service providers (ISPs) have agreed to support customers to access the Internet at local prices. A specialized software will allow ISPs to calculate user costs.

- Users must hire the service of an ISP that has an international roaming agreement in their country.

- With this agreement, you will identify an ISP in your city.

- At this destination, users can call the designated phone number of that ISP via the computer's modem, enter the login information to the network to determine your "home" ISP.

- ISP "foreign" will contact the "internal" ISP to check the authenticity of the information.

- ISP "foreign" will allow users to access the Internet, access mailboxes from mail servers in "home".

- Users will be charged at the local phone price, in addition, depending on the service price agreed by the two providers, the ISP may charge an additional charge by hour or month.

However, if you only need to exchange mail, you can think of popular free e-mail services such as Yahoo, Gmail, Hotmail, Rocketmail . Hotmail with support for POP3 to access up to 4 e accounts. -mail is available, as long as you remember the POP3 server name and ID, password.

If a subscriber of a global service such as AT&T WorldNet or IBM Global Network, you can access your account in the cities through the Internet's point-of-presence (POP) point of view. There is no need to pay for a long distance call.

In general, when the internet access fee in the world is almost cheaper than Vietnam and the free webmail services are capable of supporting POP3, the use of Internet roaming sounds old with digital subscriber line, wallet example VNN1260. However, in case you want to go online at a phone line only, you are still comfortable with Internet roaming. Subscribers to VNN1260 can connect to the Internet in 150 countries that have signed agreements, there are remote places like Panama, Guam, Marshall Islands . Details of this service, you can see here .