REDCOM Sigma Client app icon

REDCOM Sigma Client

Sigma Client is a VoIP Unified Communications client for voice, video & chat.

REDCOM Laboratories · com.redcom.sigma

Not rated yet 1K+ downloads v6.4.1 build 181 99.3 MB Android 11+ PEGI 3 · Everyone

  • Signature matches the Google Play version Details

At a glance

Latest version
v6.4.1 build 181 (861)
Updated
Oct 4, 2026 (4 days ago)
APK size
99.3 MB
Requires
Android 11+ (API 30)
CPU support
x86 32-bit, x86 64-bit, ARM 32-bit, ARM 64-bit
Graphics
OpenGL ES 2.0+
Category
Communication (app)
Listed since
Mar 20, 2021 (at least)
Permissions
20 (5 sensitive)
Website
redcom.com
Developer contact
[email protected]
Privacy
Developer's privacy policy

About this APK

REDCOM Sigma Client is an app by REDCOM Laboratories in the Communication category, listed since at least March 2021. It includes native code for x86 32-bit, x86 64-bit, ARM 32-bit and ARM 64-bit, so it runs on practically every phone.

Since version 3.3.14 build 11, the minimum Android version rose from 8.0 to 11. It asks for 20 permissions, 5 of them sensitive, including camera, record audio and read contacts. It asks for the same permissions as version 6.4 build 5.

What's new in v6.4.1 build 181

Minor bug fixes

Description

From the listing uploaded by “appupdater”.

REDCOM® Sigma® Client is a SIP-based C2 softphone that provides secure voice, video, and chat with presence on Android™ phones and tablets. Sigma Client is a stand-alone softphone app and not a VoIP service. To make calls, the app requires the REDCOM Sigma call controller. While it may work with other standards-compliant SIP and XMPP servers, we do not support third-party call and session controllers. Product Highlights: • Protects critical communications with 2048-bit RSA encryption • Supports dual registration to two or more independent SIP servers • Supports a range of standard and high-definition codecs including G.711, G.722, G.729, Opus, and Speex • Fully AS-SIP compliant Unified Communications Features: • Real-time voice • Full MLPP support • Integrated PTT • Point-to-point video • XMPP chat Other General Features: • Call forwarding • Call transfer (attended & blind) • Call hold • Call history (view & delete) • Calling number delivery • Three-way calling • Missed call notifications • Support for ICE • Call encryption (TLS/SRTP) • FIPS 140-2 validated encryption • Mutual authentication • Noise suppression • Echo cancellation (device dependent) • Provisioning • Dial plan rules • Auto start on bootup • Emergency call handling by native dialer* For more information on Sigma Client features, visit: https://www.redcom.com/products/sigma-client/ *Emergency Call Handling: When a user dials an emergency number from Sigma Client on a device with telephony support, the app is designed to pass the dialed digits to the mobile device's native dialer, where the user can then attempt to complete the emergency call via their cellular carrier’s voice network. After handing off the dialed digits to the native dialer, the app is no longer involved in the call attempt. Once placed, the emergency call and any related location services are the responsibility of the cellular carrier. By default, the app treats ‘911’ as an emergency number and passes 911 calls to the native dialer. The user can reconfigure the list of known emergency numbers within the app, which allows the user to control which dialed numbers, if any, are passed to the native dialer. Dialing emergency numbers from the app on a device without telephony support or reconfiguring the app to prevent emergency numbers from being passed to the native dialer will cause the app to process any emergency call as a VoIP call over the data network. Such calls can fail to complete due to any disruption of the app’s ability to communicate with its VoIP network service, such as power outages, lack of data network connectivity, etc. Placing a call through the VoIP network to report an emergency may also fail to direct the call to the correct emergency response center or determine the user's correct location. For these reasons, REDCOM recommends that emergency calls be placed over the cellular carrier’s network using the device’s native dialer, if available. For devices without telephony support, REDCOM recommends that users always have an alternative means of accessing emergency operator services in case of disruption of VoIP service. REDCOM will not be liable for errors, delays, costs, damages, injury, or death resulting directly or indirectly from using Sigma Client for emergency calls.

Version history

6 versions are listed, going back to v3.3.14 build 11. New versions arrive here every few months. Since v6.3 build 11 it requires Android 11+.

All 6 versions

Security & authenticity

Security rating: Trusted

Signing certificate

  • Signature matches the Google Play version Checked by the source store on Oct 4, 2026.
  • Certificate issued to “REDCOM Laboartories, Inc.” This is the certificate of the Google Play version.
  • Same certificate as the 3 other versions checked

Store checks and file details

  • Developer signature verified Oct 4, 2026
  • Validated against Google Play Oct 4, 2026
  • Signed byCN=Staff Engineer, OU=Product Release Control, O="REDCOM Laboartories, Inc.", L=Victor, ST=New York, C=US
  • Signing certificate (SHA-1)47:74:C5:89:4E:CC:83:90:51:89:31:91:50:A6:35:40:59:8F:A1:8B
  • File MD50cf2ccad5407ae3c435cbf5beb92f93e
  • Uploaded by “appupdater” Gold tier · 117,810 followers · uploading since 2020

Scans and ratings come from the source store; the certificate comparisons are AAPKs's own, made from the files' published signatures (3 other versions compared). AAPKs doesn't scan files itself — compare the MD5 and signer after downloading.

Permissions (20)

REDCOM Sigma Client requests 20 permissions, 5 of them sensitive.

Required hardware & features

REDCOM Sigma Client APK: questions and answers

Is there a version of REDCOM Sigma Client for older Android phones?

The current version needs Android 11 or later. Version 6.1.5 build 7 is the newest listed build that installs on Android 10 and later. It is an old build: apps that rely on online services may no longer connect when they are this old. Get version 6.1.5 build 7 · All versions

Can I install this APK over the version I already have?

Yes, if your installed copy is older. It is signed like the Google Play version, so Android installs it as an update and keeps your data.

Is the REDCOM Sigma Client APK safe?

No one can promise that a file is safe, but some things can be checked. The source store rates this file Trusted. Its signature matches the Google Play version. It is signed with the same certificate as the 3 other versions checked. After downloading, check that the file's MD5 is 0cf2ccad5407ae3c435cbf5beb92f93e.

Tags

More Communication apps