calls.go
func (c *CallService) GetPageIterator(data url.Values) CallPageIterator {
	iter := NewPageIterator(c.client, data, callsPathPart)
	return &callPageIterator{
		p: iter,
	}
}
func (c *CallService) GetPageIterator(data url.Values) CallPageIterator {
	iter := NewPageIterator(c.client, data, callsPathPart)
	return &callPageIterator{
		p: iter,
	}
}
// GetPageIterator returns an iterator which can be used to retrieve pages.