Operating System: Windows XP SP2 , cygwin
Version of smsd: 3.0.10
Smsd installed from: sources
Name and model of a modem / phone: Siemens MC35
Interface: serial

It happens very rarely.
some of sms are sent ( received by recipient ) multiple times , e.g. 15 or 89 .
smsd has no issues in its log ( loglevel =5 ). In the log there is only one record for each sms sent.

2009-09-09 09:10:59,5, M4: SMS sent, Message_id: 34, To: ....

All cases are with sending to another country. However there are a lot of other messages to the country with no issues.

Keke , or someone else , could you please advice with the issue ?

Even in case of an error, smsd tries sending only three times and after this the message is failed permanently. Every retry can be seen in the log. As you do not have this kind of lines in the log, there has been no retries.

89 SMS is a lot of messages, , but nothing can be done to fix this. The problem is in the GSM network, probably with a roaming partner.

In the past I visited Bulgaria and my SIM was roaming on Vivatel network. Finnish operator I use is Saunalahti. My server in Finland sent me an alert using SIM from TeliaSonera. The SMS was surely sent once, but I received it about 50 times during the one day. This same happened with an ordinary phone and different SIM too, but in both cases the sender used SIM from TeliaSonera.

Thank you , keke !

Will monitor system further.