Connection details


Clickatell has a compliance test and production SMSC. Initially, you’ll need to connect to the compliance test SMSC and perform compliance testing. After this, you’ll be able to connect to the production SMSC. Each SMSC has two ports available to connect to, one for unencrypted connections (using the standard port number below), and one for creating SMPP-over-SSL/TLS encrypted connections (using the SSL/TLS port number below).



Standard Port


Compliance Test









The ESME should use its API username, API password and API ID in the supported bind PDUs to authenticate its connection with the SMSC. Please see the bind PDUs in the “PDU Details” section for more detailed information.

Note: The ESME’s API username and API password can be different from the Developers’ Central account username and password.


The ESME is allowed to connect eight transmitter, eight receiver, and eight transceiver binds per API ID to the SMSC. The ESME can only create one SMPP API in Developers’ Central. Contact Clickatell support if you require more SMPP APIs. 

Note that there is no throughput limitation, but also no guaranteed throughput, on a bind. However, a single SMPP API should be enough if the ESME configures its SMPP client software with the maximum number of binds and is able to use “windowing” (asynchronous sending).


Clickatell has an SSL/TLS-enabled SMSC if you want to use encryption of the data sent between the ESME and the SMSC.

To use SMPP-over-SSL/TLS, connect to the Compliance Test or Production SSL/TLS port with your SSL/TLS enabled SMPP client software.  It is not required to specify a client certificate during the SSL/TLS handshake unless your SSL/TLS enabled SMPP client software requires it, in which case you would then need to specify your own client certificate. Clickatell’s certificate is issued by Digicert, whose intermediate and root certificates are already included in common trust stores across most operating systems and applications. However, if your SSL/TLS-enabled SMPP client software is using a custom trust store or certificate pinning, you must add the Digicert intermediate and root CAs to your application’s trust store. The instructions for doing this vary based on the application or platform. Please refer to the documentation for the application or platform you are using. You can also Contact Clickatell support to get the Clickatell server certificate if you need to add it to your application’s trust store.

Clickatell’s SMPP server supports the following SSL/TLS versions:

  • SSLv3
  • TLSv1
  • TLSv1.1
  • TLSv1.2

Please try to connect with TLSv1.2 since the older SSL/TLS versions might be deprecated in the future.


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