Evolutionary Step

VoIP (Voice over Internet Protocol) is the next evolutionary step in telephone service from its beginnings over a hundred years ago as Centrex or Central office Exchange (where telephone service is provided via switching connections in the CO-Central Office). PBX-Private Branch exchange services emerged as customers with large organizations wanted to control services/features and provide internal or private systems administration of multiple carriers at their corporate or branch offices.

With the advent of VoIP-Voice over Internet Protocol also referred to as IPT-Internet Protocol Telephony, new features, capabilities and integration with office and computing applications emerged.

The VoIP in SIP

Key VoIP Options:

  1. IAS-Integrated Access Service
    The primary benefit of IAS-Integrated Access Service is the seamless integration of existing data networking equipment plus prioritized voice with dynamic data bandwidth allocation. VoIP, local or long distance connections are completed by the carrier or provider.
  2. HIPT-Hosted Internet Protocol Telephony
    The primary benefit HIPT-Hosted Internet Protocol Telephony is an outsourced hosted solution like a hosted website of IP voice telephony with dynamic data. This is often referred to as “everything is data” networking.
  3. MIPT-Managed Internet Protocol Telephony
    The primary benefit of MIPT-Managed Internet Protocol Telephony is a provider administered service of all CPE-Customer Premise Equipment and data devices on the IP voice network to ensure performance and QoS.

SIP & Integrated Access Devices

SIP Trunking works with traditional TDM-Time Division Multiplexed PBX-Private Branch Exchange telephone systems to merger voice trunking with high speed data access. The IAD (Integrated Access Device) dynamically (automatically) manages data and voice packets with priority given to voice for high-quality performance.


IADs provide the service known as integrated access also known as converged access (flex services) a communications service which provides voice telephony connections as well as high speed data communications over the same T-1 circuit. While integrated access service has been around for more than five years, new dynamic bandwidth and other capabilities are now available.  While the difference between integrated and converged access is often more marketing than actual, integrated access usually refers to as fixed allocation of bandwidth. For example, the carrier would provide up to 50% of the bandwidth or 12 channels for telephone connections and the remainder or 768 kilobits per second for internet or wide area data networking. With converged access, as shown here, bandwidth is not fixed but allocated based on need. Voice is prioritized for high quality of service or QoS. One carrier provides up to 10 high quality and up to 40 low quality voice calls with the remainder of the bandwidth available for data. This means if no one is the phone, the entire T-1 bandwidth is available for data communications. In addition, VoIP-Voice over Internet Protocol and other features are available depending on specific carrier offerings.

If there is no PBX, the SIP Trunking IAD supports analog phones. SIP Trunking also supports a “hybrid” mix of IP deskset telephones, PC-based softphone IP and analog telephones.