send Massive push notification to GCM - php

Question

I have to send Push Notifications with different messages for large number of devices(More than 10k devices per day).But sometimes its not receiving all of the devices.I set up a function pushNotificationToUsers($heading,$message,$registraionids) to send the push notification and I am not sure about my method is correct ,if i am wrong please correct me.
function pushNotificationToUsers($heading,$message,$registraionids){
//array of registration ids in $registraionids
$key="xxxxxxxxxxx";
// Set POST variables
$url = 'https://android.googleapis.com/gcm/send';
$fields = array(
'registration_ids' =>,$registraionids,
'data' => array( "message" => $message,"title"=>$heading,"soundname"=>"beep.wav" ),
);
$headers = array(
'Authorization: key=' . $key,
'Content-Type: application/json'
);
// Open connection
$ch = curl_init();
// Set the url, number of POST vars, POST data
curl_setopt( $ch, CURLOPT_URL, $url );
curl_setopt( $ch, CURLOPT_POST, true );
curl_setopt( $ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt( $ch, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch, CURLOPT_POSTFIELDS, json_encode( $fields ) );
// Execute post
$result = curl_exec($ch);
// Close connection
curl_close($ch);
}
I'm using php in my serverside

Answer 1

For Android,
The message size limit in GCM is 4 kbytes.
https://developer.android.com/google/gcm/server.html#params
The message size limit in C2DM is 1024 bytes. (DEPRECATED)
https://developers.google.com/android/c2dm/#limitations
For iOS,
in iOS the size limit is 256 bytes, but since the introduction of iOS 8 has changed to 2kb!
https://forums.aws.amazon.com/ann.jspa?annID=2626
Also, see below stuffs
After Google replaced C2DM with GCM, they took off all limits.
http://developer.android.com/google/gcm/c2dm.html#history
The only limits you run into the GCM documentation is this:
http://developer.android.com/google/gcm/adv.html#lifetime
I think this answer is enough clear for your question.