c2dm과 gcm 은 호환되지 않는다.

 

 

http://developer.android.com/google/gcm/c2dm.html

Relationship between C2DM and GCM

C2DM and GCM are not interoperable. For example, you cannot post notifications from GCM to C2DM registration IDs, nor can you use C2DM registration IDs as GCM registration IDs. From your server-side application, you must keep keep track of whether a registration ID is from C2DM or GCM and use the proper endpoint.

As you transition from C2DM to GCM, your server needs to be aware of whether a given registration ID contains an old C2DM sender or a new GCM project number. This is the approach we recommend: have the new app version (the one that uses GCM) send a bit along with the registration ID. This bit tells your server that this registration ID is for GCM. If you don't get the extra bit, you mark the registration ID as C2DM. Once no more valid registration IDs are marked as C2DM, you can complete the migration.