Export Gmail Contacts to CSV
Log in to your Gmail. Click the Gmail icon (top left) and select Contacts from the dropdown.

You will reach the Gmail Contacts interface.
Click "More" and select "Export".
Select which contacts to export and choose Google CSV format. Click Export.
Open the exported file in Excel/OpenOffice. Select the correct import format as shown below. Click OK.
The phone numbers will be in the last column — we need to reformat the file to match iSMS CSV format (phone number first).
Log in to your iSMS account → SMS → Compose SMS → CSV Compose → click "CSV Sample" to download the correct format template.
Reformat your Gmail CSV to match the iSMS sample. Add % before and after column titles (e.g. %name%).

Save as Text CSV (.csv) format.
Upload your reformatted CSV in iSMS CSV Compose to send your messages.