Company: SONM
Filing Date: 2025-06-26
Form Type: DEFA14A
Source: 0001641172-25-016672
Chunk: 0

Company: SONIM TECHNOLOGIES INC
Filing Date: 2025-06-26
Form: DEFA14A
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the

Securities Exchange Act of 1934</div>

Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

| ☐ | Preliminary                                                       
 Proxy Statement                                                   |
| ☐ | Confidential,                                                     
 for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
| ☐ | Definitive                                                        
 Proxy Statement                                                   |
| ☒ | Definitive                                                        
 Additional Materials                                              |
| ☐ | Soliciting                                                        
 Material under §240.14a-12                                        |

<div align='center'>Sonim Technologies, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)</div>

Payment of Filing Fee (Check all boxes that apply):

| ☒ | No                                                                                              
 fee required                                                                                    |
| ☐ | Fee                                                                                             
 paid previously with preliminary materials                                                      |
| ☐ | Fee                                                                                             
 computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11 |

On June 26, 2025, the following email was sent by Clay Crolius, Chief Financial Officer of Sonim Technologies, Inc. (the “Company”), to the Company’s employees:

Team,

Many of you have been asking when and how you will receive the WHITE card for proxy voting. If you haven’t already received communication from your broker (e.g. E-Trade) or if you have questions, please contact your broker directly or the Company’s proxy solicitor, Sodali:

430 Park Avenue, 14th Floor,

New York, NY 10022

Banks and Brokers Call: (203) 658-9400

Stockholders Call Toll Free: (800) 662-5200

E-mail: SONM@investor.sodali.com

Voting closes July 17, 2025 at 11:59PM Eastern Time.

Best regards,

Clay

Clay Crolius

CFO

Sonim Technologies

Important Information and Where to Find It

Sonim has filed with the SEC a definitive proxy statement on Schedule 14A, containing a form