Computer Supported Telecommunications Applications | NFON UK [Contact](# "Contact") ![](/web-assets/f/290788/40x40/d98615a3ea/nfon-sales-contact.svg) Sales & General * [Talk to Sales](tel:+443303838000) * [Write to us](/gb/request-information) Search * [![Products](https://a.storyblok.com/f/290788/40x40/539cd331b9/nfon-products.svg) Products](#) Call & Work ![AI icon](/assets/ai_icon.webp) + [Cloud Telephony](/gb/products/cloud-telephony/) + [SIP Trunk](/gb/products/enablement/) + [Devices](/gb/products/devices) Build & Automate ![AI icon](/assets/ai_icon.webp) + [Assistants](/gb/products/ai/assistants) + [Bots](/gb/products/ai/bots) + [AI Agent Studio](/gb/products/ai/agent-studio) Engage & Support ![AI icon](/assets/ai_icon.webp) + [Contact Center](/gb/products/customer-contact/) Integrations & Add ons + [Integrations & Add ons](/gb/integrations/) * [![Solutions](https://a.storyblok.com/f/290788/40x40/da156cbbb8/nfon-solutions-industries.svg) Solutions](#) Industries + [Health & Wellness](/gb/solutions/health-wellness) + [Retail & E-Commerce](/gb/solutions/retail) + [Finance & Legal](/gb/solutions/finance-insurance) + [Travel & Hospitality](/gb/solutions/hospitality) + [Public Sector](/gb/solutions/public-sector) + [Energy](/gb/solutions/energy) Success stories + [Customer Stories](/gb/customer-stories/) * [![Partnerships](https://a.storyblok.com/f/290788/36x36/7bd105c67d/nfon-partner.svg) Partnerships](#) Partner with NFON + [Partner](/gb/partner/become-partner) + [NGAGE](/gb/partner/partner-programme) Partner Portal + [Partner Portal](https://partners.nfon.com/) * [![Help Center](https://a.storyblok.com/f/290788/40x40/d01fbb4f30/help-nfon.svg) Help Center](/gb/help-centre) * [Login](https://start.cloudya.com/ "Login") * United Kingdom + [International](/en) + [Deutschland](/de) + [España](/es) + [France](/fr) + [Italia](/it) + [Österreich](/at) + [Polska](/pl) + [Portugal](/pt) + [United Kingdom](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/csta) [![NFON Logo](/assets/logo-nfon.svg)](/gb/ "NFON Home") * [Products](#) ![](/web-assets/f/290788/36x36/a9f3ceed6f/nfon-call-work.svg) Call & Work ![AI icon](/assets/ai_icon.webp) Seamless communication ![](/web-assets/f/290788/36x36/d03c61cf40/nfon-build-automate.svg) Build & Automate ![AI icon](/assets/ai_icon.webp) AI Automation ![](/web-assets/f/290788/36x36/106823b73b/nfon-engage-support.svg) Engage & Support ![AI icon](/assets/ai_icon.webp) Omnichannel support ![](/web-assets/f/290788/36x36/50b60f5411/nfon-integrations-add-ons.svg) Integrations & Add ons Connect Teams & CRMs + [![](/images/products-call-work-cloudteleophny-navbar-int_Fjf8b.webp) ### Cloud Telephony ![AI icon](/assets/ai_icon.webp) Seamless cloud telephony for every device. High-fidelity audio with European-grade security.](/gb/products/cloud-telephony/) + [![](/images/products-call-work-siptrunk-navbar-int_ZH5NzW.webp) ### SIP Trunk Secure cloud connectivity for your existing hardware. Scales instantly with your business.](/gb/products/enablement/) + [![](/images/products-call-work-devices-navbar-int_Z2dP6.webp) ### Devices Professional telephones and hardware designed for clear calls and all-day comfort.](/gb/products/devices) + [![](/images/products-build-automate-assistants-navbar-int_2ghUIJ.webp) ### Assistants ![AI icon](/assets/ai_icon.webp) Pre-configured, plug-and-play digital roles like FrontDesk and Workdesk. Ready to deploy instantly with zero coding required.](/gb/products/ai/assistants) + [![](/images/products-build-automate-bots-navbar-int_Z1p57Vm.webp) ### Bots ![AI icon](/assets/ai_icon.webp) Prompt-driven, multi-channel conversational experiences. Automate custom customer journeys across Web Chat, Voice, and Livechat.](/gb/products/ai/bots) + [![A chatbot creation interface is shown with a readiness message, build report, agent prompt details, and created tools list, over a gradient background.](/images/products-build-agent-studio-navbar-int_Z1Y88dE.webp) ### AI Agent Studio ![AI icon](/assets/ai_icon.webp) Simply turn your ideas into AI agents for your business. Describe the task, create a working agent, then optimize it in one workspace.](/gb/products/ai/agent-studio) + [![](/images/products-engage-support-navbar-int_1xyFBE.webp) ### Contact Center ![AI icon](/assets/ai_icon.webp) Omnichannel customer service for modern teams. Manage conversations, automation, AI assistance, and customer context.](/gb/products/customer-contact/) + [![](/images/products-integrations-addons-navbar-int_Z1Ka5ea.webp) ### Integrations & Add ons Expand your capabilities and natively connect your everyday business to keep all workflows unified.](/gb/integrations/) * [Solutions](#) ![](/web-assets/f/290788/40x40/da156cbbb8/nfon-solutions-industries.svg) Industries Tailored solutions ![](/web-assets/f/290788/40x40/155f2a989d/nfon-success.svg) Success stories 54,000+ trust us + [![](/images/solutions-health-wellness-navbar-int_Z15q3kJ.webp) ### Health & Wellness Secure communication for better patient experiences and care delivery.](/gb/solutions/health-wellness) + [![](/images/solutions-retail-ecommerce-navbar-int_zUgjw.webp) ### Retail & E-Commerce Connected communication for modern retail and customer engagement.](/gb/solutions/retail) + [![](/images/solutions-finance-legal-navbar-int_1Dy5Ax.webp) ### Finance & Legal Trusted communication for regulated and security-conscious organizations.](/gb/solutions/finance-insurance) + [![](/images/solutions-hospitality-travel-navbar-int_17WoBe.webp) ### Travel & Hospitality Seamless communication for exceptional guest experiences and service.](/gb/solutions/hospitality) + [![](/images/solutions-publicsector-navbar-int_YyABB.webp) ### Public Sector Reliable communication for responsive public services and citizen support.](/gb/solutions/public-sector) + [![](/images/solutions-energy-navbar_FDoix.webp) ### Energy Reliable communication for responsive customer service, even during outages and peak demand.](/gb/solutions/energy) + [![](/images/solutions-costumerstroy-navbar-int_Z1MdOsM.webp) ### Customer Stories Real-world impact across every industry. Explore how we solve complex communication challenges for Europe’s leading brands.](/gb/customer-stories/) * [Partnerships](#) ![](/web-assets/f/290788/36x36/7bd105c67d/nfon-partner.svg) Partner with NFON Join the NFON network ![](/web-assets/f/290788/36x36/8c5c9a9c78/nfon-partner-portal.svg) Partner Portal Existing partner login + [![](/images/partnerships-partner-navbar-int_ZHYGKx.webp) ### Partner From onboarding to co-branded marketing, we provide the tools you need to win.](/gb/partner/become-partner) + [![](/images/partnerships-ngage-navbar-int_Zs3yY9.webp) ### NGAGE Discover our tiered rewards system designed to help you scale your business and revenue.](/gb/partner/partner-programme) + [![](/images/partnerships-partnerportal-navbar-int_2ki451.webp) ### Partner Portal Access partner tools, deal registration, training resources, and program benefits in one place.](https://partners.nfon.com/) * [Help Center](/gb/help-centre) * Search * [Login](https://start.cloudya.com/ "Login") * gb + [International](/en) + [Deutschland](/de) + [España](/es) + [France](/fr) + [Italia](/it) + [Österreich](/at) + [Polska](/pl) + [Portugal](/pt) + [United Kingdom](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/csta) * [Contact](#) [Contact](# "Contact") + ![](/web-assets/f/290788/40x40/d98615a3ea/nfon-sales-contact.svg) Sales & General Get in touch with us. ![](/images/getstarted-talktosales-navbar-int_ZMspQ4.webp) ### Talk to Sales Get a free consultation to see how NFON products can meet your needs. [+44 330 383 8000](tel:+443303838000 "+44 330 383 8000") ![](/images/getstarted-writetous-navbar-int_ZY7MOf.webp) ### Write to us Fill out our request form. Our experts will respond as soon as possible. [Write to us](/gb/request-information "Write to us") ### Computer Supported Telecommunications Applications (CSTA) [The contents of computer supported telecommunications applications (CSTA)](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/csta#section-3) [Important basic functions of computer telephony integration with CSTA](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/csta#section-4) # Computer Supported Telecommunications Applications (CSTA) Computer supported telecommunications applications, or CSTA for short, refers to a protocol interface which enables the smart connection of computers and [phone systems](/gb/gb/products/cloudya). It allows computer-supported telecommunications applications to be implemented regardless of the manufacturer. Computer supported telecommunications applications was standardized by the European Computer Manufacturers Association (ECMA) and is the basis for many [computer telephony integration (CTI)](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/cti) solutions. Among other things, the protocol defines the structure and the type of messages used to control different features such as [conference calls](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/conference-call), call forwarding and switching between computer and phone system. ### The contents of computer supported telecommunications applications (CSTA) Computer supported telecommunications applications (CSTA) refers to the standardized protocol for communication between the phone system and computer software. However, the specification only contains the transmitted data. Messages are transmitted irrespective of it and can be carried out with different media and protocols. CSTA messages can e.g. be transmitted serial, via [ISDN](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/isdn) or via [TCP/IP](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/tcp-ip) network. Data is encoded via Basic Encoding Rules (CSTA Phase I, II and III) and via XML Encoding Rules (CSTA Phase III). Newer implementations often use only XML (Extensible Markup Language) for coding. Nowadays almost all manufacturers of phone systems and phone system software support and implement computer supported telecommunications applications. TSAPI (Telephony Service Application Programming Interface) and [TAPI (Telephony Application Programming Interface)](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/tapi) are CSTA-based programming interfaces. ### Important basic functions of computer telephony integration with CSTA CSTA specifies both the data messages controlling the phone system through IT and vice versa. This allows desktop-based CTI applications enabling significantly more efficient use of telecommunications options to be implemented. Calls can be connected right from the computer with just a click, or [faxes](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/efax) sent right from various computer applications. Intelligent linking of [phonebook](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/address-book) services further allows the computer to display a variety of additional details about the respective subscriber right when taking or making a call. ### Related Articles ### Computer Telephony Integration (CTI) CTI is the abbreviation for the technical term Computer Telephony Integration. It refers to a communications solution that, with the assistance of computer software, allows functions of the phone system to be used in conjunction with information stored in the computer system, such as phone numbers. CTI enables control of the phone through the PC. This allows computer software such as email programs to connect you to the telephone system with just the click of a mouse. With incoming calls, a corresponding CTI function can display information about the caller from a [CRM system](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/customer-relationship-management), such as their contact details or call history. These additional functions make communication in business more efficient and allow for the better exchange of information. To operate Computer Telephony Integration, the computer needs the appropriate software to control the system phone or communicate with the [telephone system](t3://page?uid=16). Many PBX manufacturers offer such software solutions for their devices. To facilitate the connection of CRM or back-end systems with as little effort as possible, the CTI programs usually have software modules that can communicate with popular CRM and back-end systems via standardised interfaces. For communication between the telephone system and the computer software, there are standardised protocols such as [CSTA](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/csta) (Computer Supported Telecommunications Applications). This protocol defines the type and format of the data to be transmitted without specifying the actual transport layer, thereby allowing CTI solutions to be implemented by many more manufacturers. Want to know more? [Check our leaflets](https://www.nfon.com/en/service/documentation/manuals/software)! [Computer Telephony Integration (CTI)](/gb/get-started/cloud-telephony/lexicon/knowledge-base-detail/cti) [Back](#) ![NFON Logo](/assets/logo-nfon.svg) News * [Events](https://www.nfon.com/gb/news/events/) * [Press](https://www.nfon.com/gb/news/press/) Customers * [Cloudya Login](https://start.cloudya.com/auth/login) * [Admin Portal](https://admin.nfon.com/) * [NFON Status](https://status.nfon.com/) About NFON * [Corporate](https://corporate.nfon.com/en/) * [Investor Relations](https://corporate.nfon.com/en/investor-relations/ir-at-a-glance/) * [Sustainability & ESG](https://corporate.nfon.com/en/sustainability/) * [Career](https://corporate.nfon.com/en/careers/) Legal * [GTC-SLA](/gb/legal/gtc-sla) * [Legal Notice](/gb/legal/legal-notice) * [Trust Centre](https://www.nfon.com/en/trust-center/) * [Data Protection](/gb/legal/data-protection) * [Cookie Settings](javascript:onclick=UC_UI.showSecondLayer()) © 2026 - NFON | All rights reserved.