If you are working on telephone solutions, please check
out the Ozeki VoIP SIP SDK.
It can be used to create:
- Adobe Flash video phone
- Silverlight video phone
- Web to web calls
- Web to VoIP calls
Custom SIP clients:
- Silverlight SIP VoIP client
- Flash SIP VoIP client
- C# .net SIP VoIP client
- ASP .net SIP VoIP client
- Web based SIP VoIP client
Custom VoIP solutions:
- VoIP SIP softphones
- VoIP call center clients
- VoIP IVR systems
- VoIP predictive dialer systems
- VoIP auto dialer systems
- VoIP call assistant
- VoIP call recording systems
- VoIP intercom solutions
GSM modem based wireless links vs IP SMS connections to the mobile network
In this guide you can read about how you can connect your system
to the mobile network and which connection method will best suite your
needs. You will read about Internet based SMS connections and
GSM modem/GSM phone based (wireless) connections. It is strongly
recommended to read this article, because it will help you design
a well working system.
In general, when you make a decision whether you want to use an
SMS connection or a GSM modem the first and most important thing to check
is the volume of SMS messages you expect to be sent or received in the
system. If you will send or receive less then 12000 SMS messages per day
a GSM modem will probably be a good option. If you will send or receive more, you
should consider to use some kind of Internet SMS connection.
SMS messaging with a GSM modem/GSM phone
If you wish to connect your system to the mobile
network wirelessly, you need a GSM modem or GSM phone, that you
can attach to your computer with a data cable. In this case your Ozeki
NG SMS Gateway software will operate this phone and will send and receive
SMS messages wirelessly. To setup this connection method, you need the following
Figure 1/a - Prerequisites for Ozeki NG SMS
Gateway GSM modem connection
Your checklist (for GSM modem connection):
*The SIM card will come with a plan, that will
determine how much money you will spend on each SMS.
Once you have all the prerequisites, you need
to put the SIM card into the phone or modem and you need to attach it
to your computer's serial port with a data cable. If your computer
does not have a serial port you can use an USB data cable or a USB to
RS232 converter. The quick start guide gives
you the steps to setup a GSM modem/GSM phone connection, or you can watch the
GSM modem vs GSM phone
When you setup a wireless connection, it is recommended to use a
modem instead of a standard GSM handset. The reason for this is that
standard mobile handsets tend to be unreliable. They have a battery, that is
likely to fail over time, and their software might not be very stable due to
short development cycles. Although standard handsets can be used for sending
messages, there is a good chance, that their built in SMS client software will
"eat" incoming delivery reports and incoming SMS and MMS messages, and these
messages will never make it to the PC through the data cable.
GSM modems are designed for long term use. They have simple, very reliable
software that makes SMS and MMS sending and receiving possible. They also have
an external antenna giving better signal strength and an external power supply
that is not likely to fail.
Advantages of using a GSM modem/GSM phone connection over Internet
- If you use a wireless connection to the mobile network through a GSM modem,
Internet outages will not stop your system from sending or receiving messages.
A wireless connection to the mobile network will work even if a network cable
is torn by an excavator at some construction site.
- GSM modem based SMS systems are cost efficient. It is very easy to find a
price plan, whith low or zero cost SMS tariffs when you purchase a SIM card.
- Wireless SMS systems can be setup in a very short time. You can attach
almost any mobile phone to your computer with a datacable and you can start
sending SMS messages in minutes. Although almost any mobile phone will work,
reliable GSM modem is preferred to have a reliable system.
Disadvantages of using a GSM modem/GSM phone connection:
- A single GSM modem can serve up to 12000 SMS messages per day. You can double
or triple this number by adding a second or third modem, but this SMS volume
still might not be sufficient for every system.
- A wireless connection can also fail. For example on new years eve, when
everybody is sending new year's greeting SMS to each other the GSM networks might
fail to accept messages from mobile devices.
- The mobile phone subscription on the SIM card might run out of money. If you
use a prepaid SIM card, you will not be able to send SMS messages until you top
up your balance.
- Only a fix sender address can be used. When you send out an SMS messages the
phone number of your SIM card will be the sender address of your messages.
SMS communication through the Internet (IP SMS)
Internet based SMS connections are also called as IP SMS
connections. These connections
use a TCP/IP link to connect to the Short Message Service Center (SMSC) of a
mobile network or an SMS service provider. On this TCP/IP link an upper layer
protocol is used to send and receive the messages. In order to setup this solution
you need the following prerequisites:
Figure 1/1 - Prerequisites for Ozeki NG SMS
Gateway IP SMS connection
In this case you need to find an SMS service
provider who can reach the mobile phones in your area. This SMS
service provider should be able to provide SMS service through
the Internet. To find such a provider, you can check our
website where we list some of them:
Once you have found such a provider, you need to sign up for
their service to get the connection parameters. You can use these
to configure your Ozeki NG SMS Gateway software.
When you select an operator the most important thing
is to select one that supports an official SMS protocol. There are 3 official
SMS protocols: SMPP, UCP, CIMD2. All of these protocols were designed to
serve SMS communication needs. They are asynchronous, high speed, and provide
all the functionality SMS communication requires. Some providers will offer SMS
service over HTTP. HTTP was designed to serve webpages not SMS. It adds a lot
to SMS communication and is not nearly as fast and efficient as the official
SMS protocols. If you sign up for an HTTP SMS service, there is a good chance,
that your system will not receive incoming messages and will not be able
to handle SMS delivery reports.
Although not as popular, the UCP (often referred to as UCP/EMI) and CIMD2 will
work just as well. The following pages give you setup instructions for
If your only option is HTTP, check out this guide to get instructions on how to
setup an HTTP SMS Service provider connection:
Advantages of Internet based SMS service provider connections:
The most popular IP SMS protocol is SMPP. Check out the following link on how
to configure an SMPP SMS service in Ozeki NG SMS Gateway:
- High speed. Internet SMS connections can serve up to 500 SMS messages per
- No physical device is needed.
- Problems with wireless links, such as low GSM signal strength will not
effect your system
- Flexible sender address assignment is possible. When you send out an SMS
messages you can freely specify the sender phone number.
Disadvantages of Internet based SMS service provider connections:
- Can be time-consuming finding the appropriate person and signing a contract
with a large mobile network operator to allow your system to connect to their
Short Message Service Center (SMSC)
- Can be expensive. SMS Service providers often require you a monthly fee or
a minimum monthly SMS volume.
- Takes more time to setup. Often firewalls need to be opened and parameters
need to be negotiated with the SMS service providers.
Switching from GSM modem to IP SMS connection
Our customers often start with a GSM modem connection and a lower capacity
software license first and they switch over to IP SMS connection and a higher
capacity license when the SMS traffic on their system increases. This switch
can be made seamlessly and it does not require any real change. All is needed
is a small configuration change in Ozeki NG SMS Gateway: The new IP SMS
connection should be configured and SMS traffic should be
routed to it from the old GSM modem connection.
Building a fail-safe system
If possible it is best to have both a wireless and an IP SMS connection at the
same time and Ozeki NG SMS Gateway should be configured
to use the IP SMS connection when available, and if the IP SMS connection fails
for whatever reason, the software should switch over to the wireless connection
automatically to keep the SMS communication working. This automatic failover
switching can be setup by installing two service provider connections and by
configuring a backup route in Ozeki NG SMS
To sum it up
Whatever your needs are, it is worth to spend some time on picking the appropriate
connection method. In all cases Ozeki NG SMS Gateway will be a good choice to
manage the connection. If you have Ozeki NG SMS Gateway installed you can check
the "Add service provider" link on the Management console to find out more
If you don't have Ozeki NG SMS Gateway installed, I recommend you to proceed to
the download page:
Download Ozeki NG SMS Gateway!