SMS backup
In most mobile phones, if you go to the “Messages” menu, select “Message settings”, then “Text messages”, besides the standard settings, you can see the “Use packet data” option, but unfortunately many operators are very reluctant to tell ( and more provide ) about the possibility of sending short messages. Let's see why operators generally do not use the ability to send short messages through their packet network, providing a service - SMS over GPRS .
The above option means nothing more than the ability to send and receive short text messages via the operator’s packet network ( PS Core Network ), using radio resources allocated specifically for packet transmission (GPRS / EDGE) without affecting the voice channels (time slots ).
On the one hand, this option should be very interesting for operators, since increases the capacity of simultaneously sent and received messages via radio interfaces, optimizes the network, but on the other hand the cost of sending a text message 160 characters long through a packet network is minimal, so the question of the cost of "real" SMS ...
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According to the standards for packet data transmission in mobile networks, after the subscriber performed the GPRS Attach procedure, i.e. passed authentication and authorization in the operator’s network and didn’t manage to activate more than one PDP Context 'a, only one function is available - SMS over GPRS (for more details on the authentication process in the operator’s packet network, see the article “ Inside GPRS. Part 2 ”)
If we consider the short message service as a whole, then there are several key features (procedures) that can be provided to the end user:
Let's now take a look at the technical side of the issue and determine the necessary conditions for the provision of such functionality through the mobile operator's packet network.
I just want to make a reservation that the SMS service is quite easy to adapt for transmission via the operator’s packet network, and there is no need to introduce new network elements, as well as any new transmission protocols, it’s enough to implement standardized connectivity interfaces between already existing network elements + write configuration data to all involved network elements.
In order to provide such a service, SGSN 'a is needed, a network element that authenticates and authorizes subscribers, as well as being a transport link in the packet transmission of subscriber data.
Conditions under which the SMS over GPRS option will be available on SGSN:
Moreover, it should be noted that the last two interfaces are optional and are connected at the request of the operator. In addition to having the necessary interfaces on the SGSN side, it is necessary to redefine the priority way of sending short messages on the subscriber’s mobile terminal (see the first paragraph — select “Use packet data”) + naturally, activate the functionality of sending SMS messages on the SGSN itself.
Let us make a small digression from our main topic and give a little explanation to the diagram above.
Some more conditions that can "affect" the ability to send / receive SMS messages through a packet network are some parameters in the subscriber profile in the HLR related to voice services, since The “standard” SMS sending scheme is closely intertwined with voice services:
In principle, there is a distinction between bans (barring) of voice services and SMS messages, but some devices do not correctly handle these bans, so the presence of bans on voice services may affect the ability to send SMS over GPRS.
In addition to the above, to simplify the implementation of the functionality of SMS over GPRS, is provided, the so-called. SMS Routing Settings on the SGSN side, which ensures correct delivery of messages without the need to make any changes on the subscriber side, in terms of changing SMS centers.
As an example, let's consider what the difference between receiving a short message (MT-SMS), through the "standard" message transmission channels, compared to receiving the same message through the operator's packet network, will be radically different.
As you can see from the diagram above, the procedure for delivering an SMS message according to the “standard” scheme is in principle no different from sending short messages through a packet network, except for the fact that the key element controlling and controlling the transfer of a message instead of MSC / VLR is SGSN. This situation is the case with sending SMS (MO-SMS) messages via the packet network, in comparison with the “standard” scheme.
As we can see from the entire description above, the introduction of additional functionality for sending SMS messages through the operator’s packet network does not make it particularly difficult on an already existing network, but at the same time allows optimizing the entire network and providing additional functionality to subscribers.
Summarize all the information on the service SMS over GPRS and identify it
limitations:
and benefits:
But the question why in the CIS territory this functionality has remained unclaimed remains open ... either the operators are not aware of this functionality, or they don’t want to implement, or something else ... :)
UPD. A small clarification: to fully verify this functionality, you need to perform the GPRS Attach procedure (on Nokia, you can choose a permanent connection to the operator’s packet network: “Menu” -> “Device connection” -> “Packet data” -> “Packet connection” -> “Permanent access. ”At the same time, the letter“ G ”[“ E ”] usually appears, which symbolizes that you have passed the authentication procedure in the operator’s packet network
A small assistant:
BSC - Base Station Controller
BSS - Base Station Subsystem
BTS - Base Transceiver Station
CAMEL - Customized Applications for Mobile Enhanced Logic
GGSN - GPRS Gateway Service Node
GMSC - Gateway MSC
HLR - Home Location Register
IN - Intelligent Networks
IWMSC - InterWorking Mobile services Switching Center
MS - Mobile Station
MSC - Mobile Switching Center
PCU - Packet Control Unit
PDP - Packet Data Protocol
SCF - Service Control Function
SCP - Service Control Point
SSF - Service Switching Function
SGSN - Serving GPRS Support Node
SMS - Short Message Service
SM-SC - Short Message Service Center
Related link (en):
Intro
The above option means nothing more than the ability to send and receive short text messages via the operator’s packet network ( PS Core Network ), using radio resources allocated specifically for packet transmission (GPRS / EDGE) without affecting the voice channels (time slots ).
On the one hand, this option should be very interesting for operators, since increases the capacity of simultaneously sent and received messages via radio interfaces, optimizes the network, but on the other hand the cost of sending a text message 160 characters long through a packet network is minimal, so the question of the cost of "real" SMS ...
')
According to the standards for packet data transmission in mobile networks, after the subscriber performed the GPRS Attach procedure, i.e. passed authentication and authorization in the operator’s network and didn’t manage to activate more than one PDP Context 'a, only one function is available - SMS over GPRS (for more details on the authentication process in the operator’s packet network, see the article “ Inside GPRS. Part 2 ”)
If we consider the short message service as a whole, then there are several key features (procedures) that can be provided to the end user:
- Mobile-Originated SMS ( MO-SMS ) - the ability to send short messages from the subscriber’s terminal (MS).
- Mobile-Terminated SMS ( MT-SMS ) - the ability of the SM-SC to deliver a short message to the subscriber's terminal (MS).
- Alert Service Center ( SC ) - according to this procedure, the SM-SC, which “services” a particular subscriber, will be informed via the HLR that the subscriber terminal (MS) is ready to receive short messages. This procedure is used in two cases:
- The mobile terminal (MS) of the subscriber informs that it is active, if it is not available until that moment.
- The mobile terminal (MS) of the subscriber informs that he already has enough memory “on board” to receive messages after it was refused to receive SMS messages due to memory overflow on the terminal itself.
Let's now take a look at the technical side of the issue and determine the necessary conditions for the provision of such functionality through the mobile operator's packet network.
Technical requirements
I just want to make a reservation that the SMS service is quite easy to adapt for transmission via the operator’s packet network, and there is no need to introduce new network elements, as well as any new transmission protocols, it’s enough to implement standardized connectivity interfaces between already existing network elements + write configuration data to all involved network elements.
In order to provide such a service, SGSN 'a is needed, a network element that authenticates and authorizes subscribers, as well as being a transport link in the packet transmission of subscriber data.
Conditions under which the SMS over GPRS option will be available on SGSN:
- availability of Gb interface with base station subsystem ( BSS )
- the presence of Ge interface for the interaction of CAMEL services, i.e. interfaces to billing platforms (GSM-SCF - interfaces between SGSN and IN platforms for pre-paid subscribers)
In the case of MO-SMS (the message is sent from the mobile terminal), the SGSN requests "permission" from the SCP platforms (IN platform) to send a short message to the pre-paid subscriber. In the absence of the necessary balance of funds in the prepaid subscriber account, the IN platform will deny the ability to send messages. If the SGSN receives an “approval” for the opportunity to provide sending an SMS message, then after successful delivery, the SCP (IN) platform will be notified of this event and will also update the balance of funds on the subscriber’s account for sending the message. - Gr presence between SGSN and HLR
- Gf interface between SGSN and EIR (check subscriber equipment - IMEI Check procedure)
- Gd interface between SGSN and SMS-GMSC
Moreover, it should be noted that the last two interfaces are optional and are connected at the request of the operator. In addition to having the necessary interfaces on the SGSN side, it is necessary to redefine the priority way of sending short messages on the subscriber’s mobile terminal (see the first paragraph — select “Use packet data”) + naturally, activate the functionality of sending SMS messages on the SGSN itself.
Let us make a small digression from our main topic and give a little explanation to the diagram above.
First, we see from the scheme that there are interfaces intended only for signaling between network elements, as well as interfaces designed for both signaling and data transmission between network elements. The main difference in these two types of interfaces is that the signal interfaces can "process" messages of different subsystems and SS7 protocols, and on interfaces for data transfer, in addition to this, it is also possible to transfer payload from / to users. For example, the Gr interface between SGSN and HLR serves mainly to receive / modify / update service information in the subscriber profile, and packets from / to the subscriber pass through the Gn interface.
Secondly, I would like to draw your attention to the fact that the Gb interface is the link between the SGSN and the base station controller ( BSC ), but actually connects the SGSN with special boards for packet data processing (PCU), which are part of the BSC. It is these cards that are the capacitive characteristic of packet transmission (GPRS / EDGE) of data on the base station controller (BSC).
Thirdly, if you pay attention to the Ge interface, you can see that it actually connects some component parts both on the SGSN side and on the SCP (IN) side of the platform. These components are special logic modules in terms of SS7 - gprsSSF for SGSN and gsmSCF for SCP, which are implemented programmatically on the specified network elements.
Some more conditions that can "affect" the ability to send / receive SMS messages through a packet network are some parameters in the subscriber profile in the HLR related to voice services, since The “standard” SMS sending scheme is closely intertwined with voice services:
- BAOC - BArring of Outgoing Calls (barring outgoing calls)
- BOIC - Barring of Outgoing International Calls (barring outgoing international calls)
- BOIH - Barring of Outbound International Calls (excluding outgoing international calls, except those addressed to the subscriber’s home network)
In principle, there is a distinction between bans (barring) of voice services and SMS messages, but some devices do not correctly handle these bans, so the presence of bans on voice services may affect the ability to send SMS over GPRS.
In addition to the above, to simplify the implementation of the functionality of SMS over GPRS, is provided, the so-called. SMS Routing Settings on the SGSN side, which ensures correct delivery of messages without the need to make any changes on the subscriber side, in terms of changing SMS centers.
Mobile-Terminated SMS Transfer
As an example, let's consider what the difference between receiving a short message (MT-SMS), through the "standard" message transmission channels, compared to receiving the same message through the operator's packet network, will be radically different.
As you can see from the diagram above, the procedure for delivering an SMS message according to the “standard” scheme is in principle no different from sending short messages through a packet network, except for the fact that the key element controlling and controlling the transfer of a message instead of MSC / VLR is SGSN. This situation is the case with sending SMS (MO-SMS) messages via the packet network, in comparison with the “standard” scheme.
Summary
As we can see from the entire description above, the introduction of additional functionality for sending SMS messages through the operator’s packet network does not make it particularly difficult on an already existing network, but at the same time allows optimizing the entire network and providing additional functionality to subscribers.
Summarize all the information on the service SMS over GPRS and identify it
limitations:
- support of the subscriber’s mobile terminal is necessary (in principle, this is no longer a limitation, since most of the devices will support this functionality)
- GPRS / EDGE coverage for operators is usually “weaker” than GSM voice service coverage
- Reducing the cost of sending SMS messages for operators, to which they do not always agree ...
and benefits:
- The SMS_over_GPRS sending rate is set at up to 30 messages per minute, while with the “standard” scheme, the speed varies from 6 to 10 messages per minute (
only “Shhhhhhhhhhhhhhh! :) - opportunity to reduce the cost for messages transmitted through the packet data channels
- load reduction + network operator optimization
But the question why in the CIS territory this functionality has remained unclaimed remains open ... either the operators are not aware of this functionality, or they don’t want to implement, or something else ... :)
UPD. A small clarification: to fully verify this functionality, you need to perform the GPRS Attach procedure (on Nokia, you can choose a permanent connection to the operator’s packet network: “Menu” -> “Device connection” -> “Packet data” -> “Packet connection” -> “Permanent access. ”At the same time, the letter“ G ”[“ E ”] usually appears, which symbolizes that you have passed the authentication procedure in the operator’s packet network
A small assistant:
BSC - Base Station Controller
BSS - Base Station Subsystem
BTS - Base Transceiver Station
CAMEL - Customized Applications for Mobile Enhanced Logic
GGSN - GPRS Gateway Service Node
GMSC - Gateway MSC
HLR - Home Location Register
IN - Intelligent Networks
IWMSC - InterWorking Mobile services Switching Center
MS - Mobile Station
MSC - Mobile Switching Center
PCU - Packet Control Unit
PDP - Packet Data Protocol
SCF - Service Control Function
SCP - Service Control Point
SSF - Service Switching Function
SGSN - Serving GPRS Support Node
SMS - Short Message Service
SM-SC - Short Message Service Center
Related link (en):
Source: https://habr.com/ru/post/86980/
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