It is important to note that the landscape of companies at the forefront of 5G technology is continuously evolving, but here are ten companies that have made significant contributions:

1. Huawei Technologies Co., Ltd.
2. Ericsson
3. Nokia Corporation
4. Samsung Electronics Co., Ltd.
5. Qualcomm Incorporated
6. ZTE Corporation
7. AT&T Inc.
8. Verizon Communications Inc.
9. Cisco Systems, Inc.
10. Intel Corporation

Please keep in mind that this list may vary depending on factors such as geographical location and specific areas of expertise, as different regions and industries might have a focus on different players in the 5G market.