Introducing certain delay between messages

[Rodrigo Montiel]

Hi list,

I was researching a little bit about how to introduce a sleep() function before each message is sent.
The reason here is because in my country we are being blocked by telcos  for any massive sms campaign attempt in order to preserve the gsm network.

I have download the latest version of gnokii/smsd and compiled as it is shown below:

 Host system:        linux-gnu
    Gnokii version:     0.6.31
    Xgnokii version:    1.0
    SMSD version:       1.5.2
    X (GTK+) support:   no
    smsd support:       yes
    Postgres support:   no
    SQLite support:     no
    MySQL support:      yes
    Debug:              yes
    XDebug:             yes
    RLPDebug:           yes
    NLS:                yes
    IrDA:               yes
    ical read support:  no
    Bluetooth:          no
    libusb support:     no
    phonet support:     no
    libpcsclite support:no
    readline support:   no
    Security:           no
    Build Shared Lib:   yes
    Build Static Lib:   yes
    Windows:            no
    Prefix:             /opt/daemon

I also have been trying to put some sleep() functions sms_send_single / sms_send_long functions, for instance:

------
static gn_error sms_send_single(gn_data *data, struct gn_statemachine *state)
{
        sleep(60);
------

Im not a guru in C coding, have made just some little (stupid) programs. 
Could you please kindly point me to which function I should review? I do not want to destroy this excellent/complex source code.

Thanks in advanced,