Digital fax server for every need

The reliable IP fax module for Cisco UCC solutions

Callisto Fax – Simply reliable

Due to its legal importance, fax communication is still very important in business communication. The Callisto Fax Server solution provides companies with all demands expected by users. From any Microsoft-based program, web interface, email, or multifunction printer (MFP), a fax can be sent, received, and viewed effortlessly from your web interface, email, Cisco Jabber, Callisto agent solution, MFP, or on any smartphone or tablet.

Callisto Fax

Suitable, fast and secure fax transmission

  • Overview
  • Features
  • Services
  • References


Universal use

Maximum productivity through universal usage options for sending and receiving faxes.

Simple to send

Every user can easily send a fax from any Microsoft-based program, web interface, email, or multifunction printer (MFP).

Receive everywhere

A fax can be received and viewed from anywhere via web interface, email, Cisco Jabber, Callisto operator solution, MFP, or any smartphone or tablet.

For everyone

Callisto Fax has a solution for everyone, whether it's a fax box for each employee, a group of employees with a hunt group line, or a centralized company fax.

No limitations

Callisto Fax supports all email clients and servers and has no limit on the number of fax box users. It supports T.38 and soft fax transmission.


Central and secured archived, this Fax module guarantees an easy search option of faxes.

All features in detail

Features from A–Z Description
Advanced functions Comprehensive cover sheet editor. Integrated with Windows Fax Services. Command line program to send a fax from other systems.
API Yes, REST API to send a fax
Deployment The Fax module is an integrated part of the Callisto platform and can be easily activated by simply assigning a license. Thanks to the Callisto appliance approach, an unrivaled fast installation is guaranteed. Prepared as an appliance image (OVA), the Callisto system can be installed on any virtual machine or physical server.
E-mail server support Any SNMP(s) email server
Fax traffic reports Possible via CDR Reporting
Gadgets Gadgets to keep track of faxes available for Jabber, Webex, smartphones, desktop and COC.
Globalized Dialing Plan (E.164) support Yes, for incoming and outgoing faxes.
High Availability Yes
Hybrid scenario support Yes, different UC platforms and connections supported via SIP trunks or PSTN Voice Gateways.
Incoming faxes Fax to e-mail. Callisto messages web interface. Callisto Gadget for Jabber, Webex, smartphone and desktop. MFP printing possible via 3rd party client software.
Multifunction printer support Yes, all with scan to email functionality.
Multi-tenant / shared instance support Yes. A single shared e-mail server for all tenants is required in this case.
Outgoing faxes E-mail to Fax. Web to Fax. Scan to Fax (with multifunction printer), Print to Fax (with Callisto Fax printer driver. Sending faxes from all Microsoft Windows programs).
Protocol and codecs SIP, SIPS, T.38, G.711 pass-through
Provisioning Manual or automatic from Cisco UCM via AXL or CSV files. Web services (REST) supported.
Scalability Up to 960 parallel fax channels on one Callisto appliance. Additional instances supported. Unlimited fax users.
Supported file formats PDF, TIFF
User experience Integrated web interface, Callisto Gadget for Jabber, Webex, smartphone and desktop and COC

We Support You in Every Situation

Sales Support

We support you in every step of the resale cycle. Depending on your Partner level, we will guide you through the sales process with your customer.

Installation and Configuration Support

We support you during the installation, configuration, and roll-out process for on-prem, managed service, or cloud projects. A satisfied partner and customer is our daily goal.

Operation and Maintenance Support

We pay attention to the highest quality and stability in each phase of our product development process. Our dedicated support team is immediately available according to defined SLA times if any incident still occurs. More…


We train and support our partners and their customers to learn how to correctly install, manage and use our Callisto products. More…

Tailored Developments

Thanks to the unique Callisto “Open Applications Management” concept, partners and their customers can add customized and tailored applications to the system anytime during runtime with no service interruption. More…


Our long-lasting expertise in UCC services and comprehensive industry know-how lead CTModule to deliver the best-in-class consultancy for your projects. More…

You Can Expect Only the Best – Because Quality Matters


The Callisto appliance solution has been successfully tested and certified with Cisco UCM V12.5. In addition to that, the Callisto platform is compatible with all popular Cisco PBX systems (UCM, UCME, BE6k/7k, HCS, Webex).

Preferred Solution Partner

CTModule has been working with Cisco Systems since 2004 and is now one of the selected manufacturers worldwide with the Cisco Preferred Solution Partner status.

Swiss Made Software

Since 2007, the “swiss made software” label stands for Swiss values such as quality, reliability and precision - especially in software development. CTModule is one of the first members of this quality label.

Callisto Fax – Your best choice


Callisto Fax is an all-rounder in terms of necessary fax transmission protocols, with many options for sending and receiving and extensive possibilities for searching, finding, and archiving faxes.


Callisto Fax supports up to 960 simultaneous incoming/outgoing faxes and an unlimited number of users with only 2-6 GB of RAM or 2-8 CPUs, securely and reliably.


Callisto Fax is diverse but simple in configuration and usage, including fax boxes. Save time and money and optimize your business operations.


Send faxes wherever you are

Printing paper, running over to the fax, using the small keyboard, and waiting for the fax to be sent is a thing of the past: Use your standard programs on your PC or mobile devices with Callisto Fax. Nevertheless, you can still use a multifunction printer (MFP) to fax directly through the Callisto Fax Server. All options are available to you:

  1. Sending faxes from any Microsoft program with the Callisto fax printer driver
  2. Upload and send the fax using a pdf/tiff file with the Callisto web interface
  3. Sending a pdf/tiff file with any email client and the Callisto fax server
  4. Sending a paper fax using a multifunction printer (MFP) with the Callisto fax server

Callisto guarantees efficient and secure faxing from any of your work devices.


Integrated with Microsoft Fax Service

With the Callisto fax printer driver, you can use the fully integrated Microsoft Fax Service solution and benefit from all the advantages of «Microsoft Fax and Scan»:

  1. Integrated contact selection from Microsoft Outlook
  2. Use individual cover pages, including cover page designer
  3. Set the priority
  4. Scheduled sending of a fax
  5. Transmission confirmation to any e-mail address
  6. and much more


Receive faxes on demand

Where would you like to receive your fax? Callisto offers you a wide range of options to receive and view a fax, wherever you are, whenever you want:

  • through Callisto web interface
  • through the separate Callisto Gadget “Messages”
  • through your usual email client
  • using the Callisto message tab for Cisco Jabber
  • using the Callisto message pane in the Callisto operator solution COC
  • using an additional SW component automatically to MFP/printer

on any PC, smartphone, tablet, or printer.

Smart reception information

Callisto Fax informs you about the receipt of a fax message on…

  • a Cisco phone through MWI and, if supported by the phone, with an XML message on the display – this also applies to faxes via email if the email client allows the display of graphics by default.
  • sticker notification in the Callisto web interface, in the Callisto messages tab, or in the Callisto messages panel
  • SMS notification to your smartphone

Secure in sending, receiving and storing

Callisto Fax is used by a large number of customers with high fax volumes and high requirements (e.g., bank orders). To give an idea, the fax transmission of a sent fax is confirmed via Callisto web interface and, if needed, also via e-mail. In the Callisto web interface or in the Callisto fax printer driver dispatch, the transmission is even displayed in real-time.

Received faxes are securely stored in the Callisto database and are part of the Callisto backup.

The simple search or the specific saving or storing of a fax is supported by all clients.

In addition to that, the intelligent Callisto authorization concept allows you to block unauthorized fax box users to send faxes.


Technology that inspires

  • Architecture
  • Requirements
  • Compatibility

Callisto architecture – The new simplicity

The Callisto platform provides the following features (without Modules and Applications):

  • all interfaces to the Cisco telephony infrastructure, provisioning (e.g., Kurmi), and 3rd party systems (e.g. (S)PMS, CRM, alarm systems, etc.)
  • Base infrastructure for import, configuration, and administration of modules, collections, and applications
  • Platform management for security, back-up/restore, update/upgrade process, licensing, log and troubleshooting capabilities
  • Dashboard and reporting
  • Single Sign-On (SSO) support
  • User and administrator management, rights management.

After licensing, modules, collections, or customized applications can be uploaded to the Callisto platform and configured in a simple and flexible way.
Callisto, with its available modules and applications, supports the following end devices and clients (depending on the use case):

  • Callisto web and telephone interface
  • Cisco endpoints (XML-enabled with push message support)
  • Cisco Jabber client with Callisto Gadgets (tabs)
  • Cisco Webex App
  • PC with Callisto operator solution and Callisto Gadgets
  • SmartPhones (iOS/Android) with Callisto Gadgets and native applications
  • Tablets (iOS/Android) with Callisto Gadgets and native applications
  • Legacy phones, DECT phones, WLAN phones according to manuals.

The Cisco PBX infrastructure (BExk, UCM, HCS) is connected to the Callisto platform via SIP trunk, AXL, and JTAPI (for COC switch solution) or SFTP (for CDRs).
Further Callisto interfaces are:

  • SIP, Secure SIP (UDP, TCP, TLS)
  • RTP, SRTP, T.38/G.711 (Softfax)
  • Cisco AXL
  • IP Socket connection
  • HTTP(S), (S)FTP
  • (S)LDAP (authentication, phone book)
  • ESPA 4.4.4 / X (Alarming)
  • REST (provisioning)
  • Application interfaces for various services or applications

The Unified Presence Server (CUPS) can be integrated as an external presence source.

Minimal requirements and resource-saving for green IT

The following requirements are needed for a proper use of the Callisto platform with the selected module(s):

Requirements Requisite/Description
Callisto Appliance (virtual Image, OVA)
  • One Callisto appliance for up to approx. 1000 parallel calls on the platform.
  • One platform is sufficient for an unlimited number of users and voicemail boxes
Virtual environment minimal: VMware ESX(i) 6.5
Callisto Appliance “Small”
  • up to 60 parallel calls
  • 2 GB RAM
  • 2 CPUs (ca. 2 GHz)
  • 80 GB hard disk space
  • 1 network connection
Callisto Appliance “Medium”
  • up to 240 parallel calls
  • 4 GB RAM
  • 4 CPUs (ca. 2 GHz)
  • 80 GB hard disk space
  • 1 network connection
Callisto Appliance “Large”
  • up to 240 parallel calls
  • 6 GB RAM
  • 8 CPUs (ca. 2 GHz)
  • 80 GB hard disk space
  • 1 network connection
  • max. 960 parallel calls per appliance
PBX (TVA/PBX) Cisco IP-PBX: CUCM, HCS, Webex (Unified CM), BExk, UCx00, UCME


The following products have been tested for interoperability with the Callisto platform.

Note: Various modules of the Callisto platform may also be compatible with other IP-PBX systems. Contact us if you have a specific project.

Manufacturer System Version
Cisco Systems Inc. Unified Communications Manager 7.x, 8.x, 9.x, 10.x, 11.x, 12.x, 14.x
Cisco Systems Inc. Unified Communications Manager Business Edition 6000 8.6, 9.x, 10.x, 11.x, 12.x, 14.x
Cisco Systems Inc. Unified Communications Manager Business Edition 7000 8.6, 9.x, 10.x, 11.x, 12.x, 14.x
Cisco Systems Inc. Unified Communications Manager Express 7.x, 8.x, 9.x,10.x,11.x, 12.x, 14.x
Cisco Systems Inc. Hosted Collaboration Solution (HCS) 8.6, 9.x, 10.x, 11.x ,12.x, 14.x
Cisco Systems Inc. Cisco UCM Cloud
Cisco Systems Inc. Cisco Unified Presence Service (CUPS) 8.x, 9.x, 10.x, 11.x, 12.x, 14.x
Cisco Systems Inc. Cisco Jabber 7.x, 8.x, 9.x, 10.x, 11.x, 12.x, 14.x
Cisco Systems Inc. Cisco Webex Client
Diverse Android for Smartphones and Tablets upon request
Apple Inc. IOS for Smartphones and Tablets upon request
CTModule AG COC Operator Console Windows 7.x, 8.x, 10.x, 11.x

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