How many attempts do we take to deliver a message?

A question that we sometimes receive is "How many times do we resend a message when we cannot deliver the message?".  The answer depends on the provider.  We are using hundreds of providers in a lot of countries to deliver your message and it is impossible to list them all.



It all starts with RingRing.  Our protocols for resending are:

  • In case of technical issues : 5 attempts, 1 attempt every 2 minutes
  • In case of no connection with the operator(s) (in the meantime, we are also contacting the operator(s):
    • During 15 minutes : 1 attempt every 2 minutes
    • After 15 minutes : 1 attempt every 10 minutes until 4 hours after the original moment of sending

The Time Validity is by Default set on 48u after the original moment of sending, except for Telenet it's 72h (they don't accept a TimeValidity < 3 days)

The Time Validity is provided to the operators when sending a message. They try to deliver a message until the moment of the Time Validity.


After the message is being sent out, we are dependent on the protocols of the provider and each provider has it's own set of protocols.  Since we cannot list them all, we are giving the protocols for the 4 most used providers:


The retry schemes of the SMSc is dependant of the error that is returned from the network.

In all cases, they store the SMS’s for 3 days and they try to deliver them at defined interval still based on the last error received from network. If a message couldn’t be delivered after exactly 3 days as of sending time, the message expires and is deleted from the SMSc DB.

In case of mobile being switched OFF, they store it and they put a flag into the HLR (customer DB). When the mobile switches ON again, the HLR knows it and sends an “Alert SC” to the SMSc to directly deliver the pending SMS’s.


Telenet & Base

The retry scheme is depending on the error received when they try to deliver the SMS. Same retry scheme is used as for MO.

They keep on trying to deliver the SMS for 7 days. Even if the subscriber is absent. If the subscriber is still absent after 7 days the SMS is deleted from the SMSC Q and notification is send to the aggregator



In any case there are two delivery attempts, one immediately after the submission and one at the end of the validity period.  The default validity period (VP) is 72h.

Default retry profiles are 1, 5, 10, 30, 3:60, 100:180, fail_msg :

1 min

5 min

30 min

3 x 60 min

100 x 180min

If the receiving Mobile Station happens to be switched off, a delivery attempt will be done the moment it is switched on under good coverage conditions.

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