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What is SMPP?

Short Message Peer to Peer is a stateful asynchronous TCP protocol that enables clients and servers to communicate by sending PDUs back and forth, in order to send and receive SMS messages as well as delivery reports.

The protocol is often used in the ecosystems of SMS aggregators to provide standard connectivity to each other, and in some cases even between operators and aggregators. However, if you are not operating your own SMS gateway, you would in most cases not benefit much from connecting via SMPP. Instead, we recommend taking a glance at our REST API, which allows simple and familiar means of submitting SMS messages to our systems.


We offer SMPP connectivity for select customers. Contact to get access. We use SMPP version 3.4, which is backwards compatible with version 3.3.

We recommend connecting to two hosts. When we perform maintenance, only one host is restarted at a time. By keeping a connection to two hosts, constant connectivity can be achieved.

Clients have the option to connect as either Transmitter, Receiver or Transceiver.


We have multiple SMPP servers available:


!!! Info “If you use our EU setup, replace the .com part with .eu

Most SMPP client allows some degree of configuration. Here is a selection of those that work well for our servers.

Name Value
Port 2775
TLS Port 8775
Bind type Transceiver, transmitter, or receiver.
Enquire link Every 30 seconds
Reconnect delay 30 seconds
System type Not required

Server Maintenance

We regularly deploy improvements to the SMPP software and the platform it runs on, so you may experience a session being disconnected, but you can reconnect almost immediately. As long as your client can reconnect automatically, no significant downtime or service disruption will occur.

When we roll out changes, only one server instance is taken down at a time, so if you require constant connectivity, we recommend you connect to more than one hostname. That would additionally allow you to distribute the load over multiple instances, thereby minimizing any risk a lost connection would have on your integration.


After SMPP connectivity has been enabled for your account, you can obtain your SMPP credentials from the system dashboard under “API”, “Credentials”.

Supported Features


Command Hex Note
generic_nack 0x80000000
bind_receiver 0x00000001
bind_receiver_resp 0x80000001
bind_transmitter 0x00000002
bind_transmitter_resp 0x80000002
submit_sm 0x00000004 No support for scheduling delivery times currently
submit_sm_resp 0x80000004
deliver_sm 0x00000005
deliver_sm_resp 0x80000005
unbind 0x00000006
unbind_resp 0x80000006
bind_transceiver 0x00000009
bind_transceiver_resp 0x80000009
enquire_link 0x00000015
enquire_link_resp 0x80000015

Only TON values of 0 and 1 are supported for destination addresses. 0 will be interpreted as 1.

Coding Schemes

The SMPP specification contains many different possible encodings, some of which are rarely used, and some of which are unspecified. Needless to say, our SMPP software does not implement the full set of possible encodings, but only the ones most commonly in use.

We also support the older flash SMS flag in the encoding. However if possible, we would recommend using the TLV field dest_addr_subunit as recommended for forwards compatibility by the spec.

The following Data Coding Scheme values are supported:

DCS Encoding
0 IA5 / GSM-7 (GSM-7)
2 Binary
3 Latin1 / ISO-8859-1
4 Binary
6 Latin/Cyrilic / ISO88595
8 UCS-2
24 UCS-2 with flash flag
240 GSM-7 with flash flag

TLV fields

We support the following common TLV fields for submit_sm as well as one custom, which can be used to set the SMS message class.

Tag Name Size Description
0x0005 dest_addr_subunit 1 byte For flash SMS
0x0204 user_message_reference 2 bytes User assigned reference for delivery reports
0x0424 message_payload octetstring For sending messages longer than 255 octets
0x2900 message_class octetstring To send with a specific GatewayAPI messageclass

Delivery Reports

Connect with at least one transceiver or receiver to receive delivery reports. A maximum of 25 000 unacknowledged reports will be kept for 48 hours.

The order of the delivery reports is not guaranteed, so in some cases, you may get an ENROUTE before a DELIVRD.

The delivery report format is as follows:

id:1390125333 sub:001 dlvrd:000 submit date:2011181054 done date:2011181054 stat:DELIVRD err:000 text:user_message_reference
id:1390125333 sub:001 dlvrd:000 submit date:2011181145 done date:2011181145 stat:UNDELIV err:019 text:user_message_reference

The fields sub and dlvrd can be ignored.

The text is the first 20 characters of the user_message_reference TLV if submitted with submit_sm. The full reference is added in the TLV as well.

The err field is a base 10 representation of our error codes listed in SMS Errors. Since we only have three digits available, we handle SMS error codes such as 0x107E by keeping 07E and then formatting in base 10 to 126. If you need to convert back, simply add 0x1000 to the SMPP error code, and format as hex.

The stat field is the following status types:




The server self-imposes a throttle when sending PDUs to a connected client, meaning that if too many PDUs are not responded to, the server will stop sending additional PDUs.


When accepting submit_sm PDUs, the server checks the encoding and makes sure that the payload can be correctly decoded using the encoding given in the PDU. Any messages that cannot be decoded correctly will be rejected.

Delivery Reports Distribution

When connected with multiple transceivers/receivers using the same account, delivery reports will be distributed between them. So even if one connection submitted an SMS, the delivery report for that SMS can be sent back over another connection.

Priority Overwrite

The priority of a submit_sm can be overwritten after it has been accepted in certain cases. Such as when sending priority 3 messages only approved for priority 1 and 2 messages. Check the limitations for details.