The Voicemail for all your needs

Callisto Enterprise VoiceMail for Cisco UCC solutions: simple - comprehensive - flexible!

Enterprise VoiceMail – An Essential Part of Every Enterprise Solution

Nowadays, voicemail systems are still an essential part of each enterprise telephony solution to ensure availability during absences. The Callisto module VoiceMail is a modern, secure, flexible voicemail system with a wide range of possibilities in terms of application, configuration, notification, administration, and interception.

Enterprise VoiceMail

Simple – comprehensive – flexible!

  • Overview
  • Features
  • Services
  • References



Enterprise VoiceMail reliably records voice messages when a subscriber is unreachable.

Available Everywhere

The voice messages can be viewed or listened to anytime and anywhere via the web, Jabber, Webex, COC, telephone, or smartphone.


Every incoming message is displayed by the Cisco Message Waiting Indicator (MWI) on the desk phone or via stickers on the web, Jabber, Webex, COC, or smartphone, or additionally notified by SMS.

Individual Announcements

In addition to the standard greeting, Enterprise VoiceMail users can easily record up to three individual, customized greetings or import professional audio files.

Urgent Forwarding

In the case of reduced reachability, callers with urgent concerns can still be connected by pressing a key instead of leaving a message.

Linked with Other Modules

Enterprise VoiceMail is embedded in the Callisto system and can be used directly and easily from other modules.

All Features in Detail

Features from A–Z Description
Access via desktop client Ensured with Callisto Desktop App. Access password-protected. Reporting and searching of received voice messages and secured listening/deleting of the voicemail box via smartphone.
Access through email Access via SMTP server. Voice messages listening/deleting over web interface through all email clients guaranteed.
Access through extension Optional PIN-protected access. Configurations and interrogation/listening/deletion of the voice mailbox through extension guaranteed.
Access through external number Protected access by entering extension and PIN. Configurations and interrogation/listening/deletion of the voicemail box through external number guaranteed.
Access through Jabber client Password-protected access. Reporting and search of received voice messages and listening/deleting the voicemail box through Cisco Jabber tab ensured.
Access through Operator Console COC Access password-protected. Reporting and searching received voice messages and listening to/deleting the voicemail box through COC mediator solution ensured.
Access through Smartphone Ensured with Callisto smartphone app for Android and iOS. Password-protected access. Reporting and search of received voice messages and listening to/deleting the voicemail box through smartphone ensured.
Access through Web Interface Password-protected access. Reporting and search of received voice messages and listening/deleting of the voicemail box through web interface ensured.
Access through Webex client Access password-protected. Reporting and searching received voicemails and listening to/deleting of voicemail box through Cisco Webex tab ensured.
Global numbering plan (E.164 support) Yes. E.164 supported
Green-IT Lowest resource requirements in the industry with the highest performance: 2 to 8 CPU’s, 2 to 6 GB RAM, 80 GB HD, up to max. 1’000 parallel calls per image.
High Availability Yes
Integration The Enterprise VoiceMail module is an integrated part of the Callisto platform and can be easily activated with a license. Sent as an appliance image (OVA), the Callisto system can be installed on any virtual machine or physical server.
Multicluster Support Yes
Notifications MWI and text message with number, date, time of the newly received message(s) to all XML-enabled and display-equipped Cisco IP phones available. Incoming notification via signal and/or sticker ensured on all other clients.
Provisioning Manually or automatically from Cisco UCM via AXL or Microsoft AD, LDAP/OpenLDAP system, and CSV files. Web services (REST) supported.
Recording capacity With default values for acquisition speed and platform storage space: 1,800 days and 5 years. With a minimum recording speed of 3,600 days and 10 years.
Scalability Up to approx. 1’000 parallel calls on one Callisto appliance. Additional instances supported. Unlimited users/voice mailboxes.
Security HTTPS, SIPS, Password- and PIN-Security, Appliance-Security
Voice Protocols and Codecs SIP and Secure SIP (SIPS). RTP and Secure RTP. Codecs: G.711 A-Law, G.711 u-Law, GSM 6.10, G.729 Fax: T.38 and Passthrough (G.711) DTMF: RTP-NTE (RFC2833), SIP-NOTIFY/INFO.

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 Enterprise VoiceMail – Your Best Choice


Callisto Enterprise VoiceMail is very easy to install, configure, manage, use and maintain. Simplicity is a common thread throughout the Callisto system, offering various advantages with the lowest TCO.


The versatile use of Callisto Enterprise VoiceMail ranges from checking voice mail in any situation and on any device to playing user-specific announcements and being able to set voice mails with individual forwarding. Enterprise VoiceMail users can work quickly and efficiently according to their needs.


Callisto Enterprise VoiceMail guarantees the “unified” approach not only through the integration of all modern media and end devices but also in connection with other Callisto modules. This ensures a simple, efficient, and time-saving workflow process.

99.9% uptime


A recent research shows that 75% of calls fail on the first attempt. This means that the requested call partner is busy or absent. Messages received from third parties are usually incomplete, corrupted, arrive late, or not at all. Analysis of successful calls shows that 50% of calls do not require direct conversation. Typical examples include “remove messages,” confirm appointments, or complete work, etc. In addition to that, about 65% of all calls are less important than work time. It is usually sufficient to store the messages in the mailbox system, where they can be retrieved at any time.

access from everywhere

Stay Up to Date

With Callisto Enterprise VoiceMail, you always stay in touch with your business partners. You can decide when and where to handle the call, and you can delegate the message to other employees at the touch of a button. You receive notifications of incoming messages on all your different end devices, allowing you to respond immediately. Versatile functions, such as pause, forward, rewind, or delete, are available for you to listen to the stored messages efficiently. In addition to that, you are always informed about the date and time of receipt. You can change the type of greeting, redirection, or notification anytime and anywhere and turn it on or off. Even if you receive several calls at the same time, you have the option to set Callisto Enterprise VoiceMail.


Individual and Versatile

As a Callisto Enterprise VoiceMail user, you have a variety of options to configure your voice mailbox:

  • Direct call forwarding to voice mail, when busy or by a defined time
  • Forwarding to email
  • SMS notification
  • Voice mail with forwarding option
  • Set individual announcements

Callisto Enterprise VoiceMail is the perfect answer to all your needs.

Crossplatform all devices

Independent from Any End Device

The Callisto Enterprise VoiceMail solution works with a wide variety of end devices. Get wherever you are, all the information you need about incoming voice messages from all the devices and clients you use. All Cisco desktop devices are supported as well as smartphones, tablets, and Cisco Jabber or Cisco Webex tabs.

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) 6.7
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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