SIP Trunking

Delivering converged voice and data on an easy to manage trunk.

Utilize network capacity, improve ROI, and take your existing network into the future. AT&T IP Flexible Reach is a Session Initiation Protocol (SIP) Voice over IP (VoIP) trunking service that integrates voice and data on a single network. This enables you to optimize the network capacity and flexibility of your existing PBX or key system investments, and also provides the foundation for advanced services.

AT&T IP Flex Reach – a SIP Trunking Solution

Get the most out of your current equipment. By converging voice and data lines onto a single IP-based trunk, AT&T IP Flexible Reach can help you handle more traffic and:

  • Obtain better utilization of your capacity by taking advantage of unused bandwidth
  • Benefit from voice compression technology which transports more voice traffic on the same size circuit, with no appreciable loss of quality
  • Manage and control performance through web-based reporting via the BusinessDirect® Portal
  • Support connectivity with IP PBXs, traditional TDM PBXs or key systems
  • Dynamically allocate bandwidth to allow for variations in call volume and data usage such as seasonal demand, new product launches, batch jobs, etc.

Improve cost-effectiveness with SIP Trunking

Take advantage of the cost efficiencies that come with consolidating voice and data with AT&T IP Flexible Reach:

  • Single streamlined, updated network is faster, more secure and easier to manage; fewer connection points means fewer delays
  • Reduced costs and billing complexities associated with separate voice lines, phone numbers, and providers
  • Centralization of services reduces the need for physical equipment in individual locations

Invest in your future with SIP Trunking

Prepare for the next generation of your network. AT&T IP Flexible Reach replaces physical voice trunks with logical, virtual ones, which should make your network more efficient and intelligent. New applications and capabilities such as IP conferencing, instant messaging, and “presence” are easy to incorporate once you have moved to AT&T IP Flexible Reach.

*Trial offer subject to important terms, conditions and restrictions.

SIP Trunking and VPNs

Combine VPN with SIP trunking to enjoy cost-effectiveness, flexibility and security all in one networking solution. Benefits include:

  • Increased network capacity and flexibility without new investment
  • Simplified, easy-to-manage network with integrated access to local, long distance, and international voice and data
  • Voice prioritization with the ability to dynamically allocate bandwidth to accommodate variations in voice and data demand
  • Reduced costs for local and long distance voice usage, and fees for voice lines and equipment in satellite locations
  • Reliable voice quality; Class of Service (COS) allows you to optimize your voice and data application performance
  • Service Level Agreements (SLAs) for VoIP service and underlying transport
  • Built-in security of an MPLS VPN

SIP Trunking and Contact Centers

Simplify customer contact methods with IP using SIP trunks. This provides several benefits:

  • Compatibility of the technical platform reduces delays and speeds call connection time, saving you money
  • Technology is streamlined and simpler to manage, reducing support staff and enabling you to focus on your business
  • Improved efficiency and flexibility of call distribution
  • Easy to incorporate IP services such as AT&T IP Toll-Free and management tools

SIP Trunking and UC

Use SIP trunks to deliver extended collaboration and interaction to your business and customer interactions. SIP trunking provides the technical platform to allow you to add unified communications services such as:

  • Instant messaging
  • Voice, web and video conferencing
  • Email
  • Unified messaging
  • Voice calling
  • Team collaboration
  • Shared calendar access

Realize the benefits of a converged network and enjoy a full range of voice services. AT&T IP Flexible Reach is a SIP trunking service that delivers integrated voice and data access for IP PBX, TDM PBX or key system environments.

Control is in your hands

AT&T IP Flexible Reach enhances network flexibility and lets you easily manage your voice services to adapt to your needs, with features such as:

  • Virtual Telephone Numbers (VTNs) – Establish a local presence and assign telephone numbers from your desired area code to any user, regardless of where the actual person is physically located
  • Centralized call delivery – Route calls from various locations and answer them centrally, and eliminate the need for equipment in individual locations
  • Combined with MPLS VPN, Class of Service (COS) option with 25 different profiles - Optimize your voice and data application performance and manage the transport of traffic as your needs require
  • Calling plans that give you local, US long distance and international reach

Migrate to SIP trunking at your own pace

If you have a PBX or key system infrastructure, with AT&T IP Flexible Reach you can keep your own phone equipment and its associated features. Since the technology is virtual and software-based, disruption is minimal.

Our team of expert technical consultants can help you plan, design and implement the optimal SIP trunking solution that meets your unique needs. For example, we can provide solutions that support branch offices without requiring additional hardware, or that allow for alternate access to the Public Switched Telephone Network (PSTN) as backup.

Enhance the customer experience

Give your customers an improved experience with AT&T IP Flexible Reach. Features such as centralized call delivery and automated call distribution to the next free associate, provide customer benefits such as:

  • Consistent customer experience
  • Decreased wait time and busy
  • AT&T provides Service Level Agreements (SLAs) for qualifying VoIP service and underlying transport, to reinforce our commitment to delivering top-quality business class voice service.
Show Me:


  • AT&T IP Flexible Reach - A SIP Trunking Solution
  • AT&T IP Flexible Reach - A SIP Trunking Solution

    AT&T IP Flexible Reach is a managed IP trunking solution that supports inbound and outbound calling on your data network, providing unlimited on-net, unlimited local, and US long distance & international calling for your U.S. sites.  You can utilize this solution with your key system, a TDM PBX or even a certified IP PBX.
    PDF | 743KB





Case Studies




White Papers

Additional Resources

  • What is SIP?

    SIP makes your voice trunks speak the same language as your network resulting in faster, better quality and more flexible service.

    PDF | 2MB
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