COMtrexx® Next

The smallest COMtrexx appliance with the full range of Soft PBX features. Future-proof COMtrexx for expansion stages up to 40 users.

Attractively priced soft PBX from the smallest expansion levels upwards

Compact, silent and extremely power-saving

Up to 40 users with a maximum of 200 devices and 40 simultaneous calls

Secure All-IP solution with dashboard platform

Mobile Work with COMfortel SoftPhone

Your advantages in detail

Maximum productivity and minimum costs with extensions up to 40 users. The compact COMtrexx Next makes it possible! The All-IP solution offers the full range of features of a COMtrexx Soft PBX in pocket format. The mini appliance is noiseless due to passive cooling and extremely energy-saving with a consumption of significantly less than 10 watts. A professional, future-proof and modern communication system that is guaranteed to fit in any environment.

The most important facts:

  • Up to a maximum of 40 users can be licensed and 200 devices (with up to 5 devices per user)
  • Cost-effective options of the maximum number of users as a package (max. 5/10/20/30/40 users)
  • Modern and user-friendly COMtrexx user interface
  • Comfort functions such as CTI, MWI, BLF with the COMfortel D-Series
  • integrated conference option with up to 10 conference rooms that can be used simultaneously
  • roaming user function for setting up mobile workplaces (alternating workplaces)
  • central caller lists
  • Support of the COMtrexx Control Center for remote monitoring / configuration

Mobile working is easily and securely supported by optional soft clients for computers, tablets and smartphones. COMfortel SoftPhone is available for the basic voice and chat functions. Those who require more extensive UC functions and seamless integration into business processes will find the optimal UCC solution with PBX Call Assist.

Compatible products

Features & technical data

Everything you need to know about our products comes now. Scroll down for more information.

Comfort Features

  • Up to 40 parallel calls possible
  • Up to 40 users licensable
  • Automatic control centre (maximum 10 configurable)
  • Barred/approved numbers, 10 each for coming and going, total maximum 200
  • Call of any second destination in parallel to the registered primary device
  • Call data management with 18,000 data records
  • Call pick-up (e.g. from the integrated voicemail or from mobile app COMfortel SoftPhone)
  • Broker and mediate
  • Pickup
  • Protection against attacks by setting blocking lists (blocked IP addresses) and activating blocking times
  • Text before signalling (can be switched for groups and for the automatic switchboard)
  • Music on hold with switchable announcement text
  • Autoprovisioning for standard SIP phones1
  • Roaming user function
    • Enables individual users to log on and off at different telephones
    • Personal caller lists can be transferred to different workplaces
  • Centrally stored caller lists
    • User-specific caller lists are stored centrally in the system
    • Stored lists are available when a user logs on via the telephone
    • Access only possible via the user
  • Setting up groups
    • 64 call groups
    • up to 40 members per group
    • Fixed channels can be reserved for group calls
  • Logging in and logging out a user via a telephone by PIN dial-in

SIP convenience features for standard SIP phones

  • SIP-BLF, Busy Lamp Field acc. to RFC 4235
  • SIP-MWI (Message Waiting Indication), monitoring of the central voicemail and fax boxes acc. to RFC 3842
  • Pickup pre-check2

Communication platforms

  • Up to 30 internal channels can be assigned simultaneously across all conference rooms
  • Up to 10 conference rooms with 10 internal participants each (audio)

Central address books

  • 2,000 contacts
  • Separate address books for departments and multi-company operation
  • Import of VCF and CSV files
  • Address book provisioning via LDAP

VoIP telephony

  • VoIP point-to-multipoint and point-to-point connection (SIP trunking)
  • Call forwarding on busy (CFB), no reply (CFNR), unconditional (CFU) at carrier trunk, configuration dependent
  • Call deflection
  • Transfer of customer-specific calling number information with outgoing calls (CLIP no screening)
  • High voice quality through optimised echo cancellation and wideband audio with G.722
  • Compatible to standard SIP telephones
  • SIP compliant with RFC 3261
  • Reservation of speech channels
  • Support of soft clients and COMfortel Softphone
  • VoIP-Codecs: G.711, G.722
  • Dynamic internal/external VoIP channels
  • Encryption of signalling/signalling (SIPS) and voice data (SRTP) for internal calls
  • Integration of external extensions (information on the location of the telephone is taken into account in an emergency call) and mobile clients

Voicemail and fax

  • Substitute function
  • Call acceptance and individual announcements depending on calling number, time and call type
  • Remote access of the voicemail boxes incl. voice guidance
  • Message and fax forwarding via e-mail
  • Up to 40 fax mailboxes, each with 500 messages per box
  • Up to 40 voicemail boxes, each with 500 messages per box
  • Maximum 3/3 channels can be used for voicemail/fax

UCC functions

  • Call journal
  • Instant messaging for a better sharing of information
  • Contact data for local users and out of external data bases
  • Platform independent (Windows, macOS, iOS, Android)
  • Presence management with automatic status detection
  • Alignment with MS Teams
  • Call setup and ending via the PC, incl. Outlook plug-in
  • Screen sharing for convinient cooperation
  • Softphone-functions for Windows, Android und iOS
  • Up to 40 users can be licensed

COMfortel SoftPhone

  • Softclient for the base functionality SIP telefony and messaging
  • Secure and simple PBX connection from anywhere via Auerswald cloud service
  • Softphone for Windows, iOS and Android

Software interfaces

  • Access address books via LDAP
  • Support of basic CTI function via action URLs3

Installation and maintenance

  • Support of the COMtrexx Control Centre for secure remote control & backup management

Unlockable options

  • User licence: Activates all functions of the Soft PBX and is required for linking users to a device. One license must be assigned per active user with at least one terminal device.4
  • PBX Call Assist
  • System activation (necessary for operation of the system)


  • COMtrexx Next licence containers up to a maximum of 40 users are offered, each of which activates a fixed number of simultaneous floating users. If more users are required for a COMtrexx Next system, the already installed licence container must be replaced by a larger one. An extension is not possible. COMtrexx Next licence containers are not compatible with the COMtrexx VM, Advanced and Business.
1 Supported for telephone models D-600/D-400/D-210/D-200/D-110/D-100 and WS-500S/M IP-DECT systems. Also partially supported are telephone models from other manufacturers such as Yealink and Snom
2 Is only supported for the telephone models D-400/D-600 and D-210/D-200 in operation with an extension.
3 Is supported for the telephone models D-600/D-400/D-210/D-200/D-110/D-100 from Auerswald
4 The licence can be used by several users ("floating"), provided that the total number of active users corresponds to the total number of licences in the system.

Trunk lines



VoIP channels (SIP acc. RFC 3261), point-to-multipoint/point-to-point connection (SIP trunking)

40 40

VoIP codecs

G.711 and G.722

User connection



VoIP subscribers

40 40

VoIP channels (SIP acc. RFC 3261)

40 40

VoIP codecs internal

G.711 and G.722

Voicemail and fax system



Voicemail channels

3 3

Fax channels

3 3

Voicemail boxes / fax boxes

2/1 40/40

Fax standard

T.30/T.38 acc. to ITU-T

Additional connections



Ethernet port 10/100 Base-T (10/100 MBit/s, twisted pair)


Technical data



Operating voltage

Wall-mounted power supply
100–240 V AC, 50/60 Hz, 0.2 A

Output values of the wall-mounted power supply

5 V=2 A

Power consumption

2.3 to 4.3 W



Dimensions (w x h x d)

103 mm x 23 mm x 103 mm

Weight (without power supply)

approx. 165 g


Operation: 0 to 40 °C, storage: -10 to +70 °C, non-condensing



Supported operating systems

Windows 10/11, macOS, Linux

Delivery Scope

  • Base unit (without user licences)
  • Wall-mounted power supply
  • Installation and setup guide


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