turns out you need type on most of these

src/sipcentric/__init__.py

@@ -165,6 +165,7 @@ class APIObject(object):
         return self._create(parent=parent,data=self._data)
 
     def _create(self, parent, data):
+        data['type'] = self.__class__.TYPE
         self._data = self._api.post(self.__class__.makeUrl(parent=parent), data=data)
         self.id = int(self._data.get("id"))
         return self._data
@@ -212,6 +213,8 @@ class Partner(APIObject):
 
 
 class Customer(APIObject):
+    TYPE = "customer"
+
     @classmethod
     def makeUrl(cls, id=None, parent=None):
         if parent:
@@ -305,6 +308,26 @@ class Endpoint(APIObject):
     URLPART = "endpoints"
 
 
+class PhoneEndpoint(Endpoint):
+    TYPE = "phone"
+
+
+class VirtualEndpoint(Endpoint):
+    TYPE = "virtual"
+
+
+class GroupEndpoint(Endpoint):
+    TYPE = "group"
+
+
+class QueueEndpoint(Endpoint):
+    TYPE = "queue"
+
+
+class MailboxEndpoint(Endpoint):
+    TYPE = "mailbox"
+
+
 class PhoneNumber(APIObject):
     URLPART = "phonenumbers"
 
@@ -343,9 +366,9 @@ class CreditStatus(APIObject):
 
 class LinkedUser(APIObject):
     URLPART = "linkedusers"
+    TYPE = "linkeduser"
 
     def create(self, parent, **kwargs):
-        kwargs['type'] = "linkeduser"
         self.data.update(**kwargs)
         for k in ("activateUrl", "email", "recordingAccess", "owner", "enabled"):
             if k not in self._data: