Add a number/numbers to a 'send' group (excluding 'merge' groups).
Name ID of the group to add the numbers to.
The MSISDN (mobile number) you wish to add. If you want to add more than one number use a comma-delimited list.
An integer with the total of added numbers to the selected group
Specific error codes:
The group ID or name was not specified or was invalid.
A number was not of a valid format.
error code 404 is reported if the group does not exist. See General error codes.