SMPP Protocol: API to enable SMS messaging between applications and mobiles.
The SMPP (Short Message Peer-to-Peer) protocol is an open, industry standard protocol designed to provide a flexible data communications interface for the transfer of short message data between External Short Message Entities (ESME), Routing Entities (RE) and Message Centres (MC). It is a means by which applications can send SMS messages to mobile devices and receive SMS from mobile devices. This is done using an SMPP connection with a Short Message Service Center (SMSC), SMS gateway, SMPP gateway or hub.
There are three versions of the SMPP protocol specification in use. The original public version of the specification is SMPP v3.3 and was released in 1997. This was updated in 1999 to SMPP v3.4. The final version was released in 2003 and is SMPP v5.
The SMPP (Short Message Peer-to-Peer) protocol is an open, industry standard protocol designed to provide a flexible data communications interface for the transfer of short message data between External Short Message Entities (ESME), Routing Entities (RE) and Message Centres (MC). It is a means by which applications (termed ESMEs) can send SMS messages to mobile devices and receive SMS from mobile devices. This is done using an SMPP connection with an MC / Short Message Service Center (SMSC) or an RE / SMS gateway or hub.
It can also be used as an API for use with USSD, CBC and other mobile services.
SMPP is designed to support short messaging functionality for any cellular technology and has specific applications and features for technologies such as: GSM, UMTS, LTE, IS-95 (CDMA), CDMA2000 (1xRTT & 3xRTT), ANSI-136 (TDMA), iDEN
The variety of messaging applications, particularly using SMS, for which SMPP can be employed is almost boundless. Mobile Operators, Message Centre vendors, Infrastructure Providers, and application developers are continually developing new applications for SMS. SMPP is ideal as an access protocol for these applications. The following summarises typical applications of SMPP:
In order to make use of the SMPP Protocol, an SMPP session must be established between the ESME and Message Centre or SMPP Routing Entity where appropriate. The established session is based on an application layer TCP/IP connection between the ESME and MC/RE and is usually initiated by the ESME. The connection is often over the Internet and can use SMPP over TLS or a VPN to secure the connection. SMPP has been assigned TCP port 2775 by IANA, however other port numbers are often used.
There are three forms of ESME-initiated session:
Additionally, the Message Centre can establish an SMPP session by connecting to the ESME. This is referred to as an Outbind Session.
The SMPP protocol is a set of operations, each one taking the form of a request and response Protocol Data Unit (PDU) containing an SMPP command. For example, if an ESME wishes to submit a short message, it may send a
submit_sm PDU to the MC. The MC responds with a
submit_sm_resp PDU, indicating the success or failure of the request. Likewise, if an MC wishes to deliver a message to an ESME, it may send a
deliver_sm PDU to an ESME, which in turn responds with a
deliver_sm_resp PDU as a means of acknowledging the delivery.
Some operations are specific to an ESME with others specific to the MC. Others may be specific to a given session type. Referring to the
deliver_sm examples above, an ESME may send a
submit_sm to an MC only if it has established a TX or TRX session with that Message Centre. Likewise, an MC may send
deliver_sm PDUs only to ESMEs that have established RX or TRX sessions.
Operations are broadly categorised into the following groups:
The following is a list of all SMPP commands:
|bind_receiver||0x00000001||Establish a receiver bind.|
|bind_transmitter||0x00000002||Establish a transmitter bind.|
|query_sm||0x00000003||Query status of previously submitted message.|
|submit_sm||0x00000004||Submit message to the Message Center for onward delivery to mobile / short message entity (SME).|
|deliver_sm||0x00000005||Send message to ESME from MC (typically delivery receipt or mobile originated SMS).|
|unbind||0x00000006||Unbind from MC and close SMPP session.|
|replace_sm||0x00000007||Replace a previously submitted message that is pending delivery.|
|cancel_sm||0x00000008||Cancel delivery of previously submitted message(s).|
|bind_transceiver||0x00000009||Establish a transceiver bind.|
|outbind||0x0000000B||Request ESME to bind (sent by MC).|
|enquire_link||0x00000015||Initiate a check to confirm ESME/MC is still reachable.|
|submit_multi||0x00000021||Submit message to the Message Center for onward delivery to multiple mobiles / short message entities (SME).|
|alert_notification||0x00000102||Indicate to ESME that mobile subscriber has become available.|
|data_sm||0x00000103||Submit packet to MC for onward delivery to SME or from MC to ESME.|
|broadcast_sm||0x00000111||Submit message to the Message Center for onward delivery to mobiles in a specified geographical area or set of areas.|
|query_broadcast_sm||0x00000112||Query status of previously submitted broadcast message.|
|cancel_broadcast_sm||0x00000113||Cancel delivery of previously submitted broadcast message.|
|generic_nack||0x80000000||Acknowledge unrecognized or corrupt PDU.|
|Reserved for MC vendors to define|
The following libraries are available for adding SMPP protocol support to an application:
The following services can be used to test (i) an application that supports SMPP for sending SMS, receiving SMS or both, or (ii) the extent of SMPP support of an SMS gateway or Short Message Service Center:
Capturing SMPP packets using tshark/wireshark
Performing a packet capture of an SMPP session can be helpful in diagnosing problems. Wireshark and tshark can be used to capture the SMPP session and display the PDUs.
If tshark is not installed on your machine then run the following (or equivalent):
sudo yum install wireshark
To perform a capture, where TCP port 2775 is being used for SMPP:
tshark -i eth0 port 2775 -Y smpp.command_id!=0
Example command output:
$ sudo tshark -i eth0 port 2775 -Y smpp.command_id!=0 Capturing on 'eth0' 455 23.400286671 220.127.116.11 -> 172.31.39.100 SMPP 107 SMPP Bind_receiver 457 23.400600221 172.31.39.100 -> 18.104.22.168 SMPP 98 SMPP Bind_receiver - resp: "Ok" 460 23.410763283 22.214.171.124 -> 172.31.39.100 SMPP 82 SMPP Unbind 461 23.410930297 172.31.39.100 -> 126.96.36.199 SMPP 82 SMPP Unbind - resp: "Ok"
Use the following to capture to file (/tmp/s.pcap) so you can view later in Wireshark:
tshark -i eth0 -w /tmp/s.pcap port 2775
This domain was acquired in June 2019 for the purpose of being a source of reference for the Short Message Peer-to-Peer (SMPP) protocol. The objective is to return this domain back to being the main reference for SMPP. The site will include the SMPP specifications, tools and other related resources.
This domain was originally the home of the SMPP Developers Forum / SMPP Forum that later became the now disbanded SMS Forum. This site has no association with any legal owner of the protocol or successor organisation.
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