Service Availability #
Service Availability is defined as the ability of a Service to perform its required function over a stated period of time. It is reported as the percentage of time that a Service is actually available for use by the Customer within agreed Service Hours. Availability is calculated as:
Note: If a Service is partially available then the Unplanned Downtime shall be calculated in equal proportion i.e., if a service is 50% available then the unplanned downtime will be calculated as 50% x elapsed period of the incident.
Availability Measurement Period: 1 Calendar month.
SIP Trunk Endpoint | Core (1) | Non-Core (2) |
Standard Build | 99.95% | 99.50% |
Resilient Build (4) | 99.99% | 99.50% |
Notes related to Service Availability:
Core functions are defined as Gamma Switching infrastructure, transmission equipment and core network, the service that supports call routing and termination.
Non-Core functions include Gamma Support Systems, access to the portal and feature based services such as Call Divert.
Service Credits: Service credits will be applicable should the level of core service availability (Note1) not meet the target monthly percentage, as per the table below. Service Credits applied to Monthly Channel rental charges only. Service credits would need to be requested by the Customer to Gamma, with evidence of services that you feel have been impacted. Any agreed service credits would be satisfied by the issue of a credit note to be deducted from the next scheduled payment to be made to Gamma.
Build Type | Target Availability | Measured Availability | Service Credit |
Standard Build | 99.95% | 99.90%-99.94% | 10% |
99.5% – 99.89% | 15% | ||
<99.5% | 25% | ||
Resilient Build | 99.99% | 99.95%-99.98% | 10% |
99.75% – 99.94% | 15% | ||
<99.75% | 25% |
A Resilient build SIP Trunking means a Gamma approved configuration such as dual SBCs in active/standby mode offering geographic diversity. For full details of the Resilient Build options and how to access these solutions, please refer to the SIP Trunking Service Description. Please note the Service Availability and other measures with the SLA relate to the core SIP trunking service and does not include access or local CPE elements.
Fault Rectification #
Subject to the fault processes detailed in the product Service Description and Gamma Customer Service Plan, the following definitions will be applied to faults raised on the SIP Trunking product:
Severity | Description | Time to Resolve |
Priority 1 | Critical Fault Loss of service – Multiple resellers/services affected | 4 clock hours |
Priority 2 | High – Loss of service single reseller or service | 8 clock hours |
Priority 3 | Medium – Disrupted service – multiple or single reseller or service | 3 working days |
Priority 4 | Low – Single number destinations/QOS | 7 working days |
Note: Service credits are not applicable against Fault Rectification performance metrics.
SIP Trunking Call Quality Performance #
As a means of determining and measuring the call quality of the SIP Trunking service, Gamma measure the call quality of calls passing through the Gamma core IP network and Session Border Controllers (SBCs).
The performance is measured using Perceptual Evaluation of Speech Quality (PESQ) score that cover a scale from 1 (bad) to 5 (excellent) for call quality. The Gamma SIP Trunking Product supports the following codecs, G.711 and G.729 for external call termination.
The PESQ score targets for the supported CODECs for the Gamma SIP Trunking product are as follows:
Codecs | Mean Average PESQ Score | Period |
G.711 | 4.1 | One Calendar Month |
G.729 | 3.7 | One Calendar Month |
The targets are measured from probes within the Gamma Network auto generating test calls every 10 minutes through the SIP Trunking network infrastructure. These performance measures apply to the performance provided within the core Gamma network.
Service Provisioning #
The standard SIP Trunking endpoint is a self-provisioned activity, performed by the reseller on the Gamma portal; the key time dependencies being the installation and availability of the access link and number porting (if required).
The following performance indicators are applicable to SIP Trunking Service Provision:
Activity | Time to Complete | Availability |
Portal – Endpoint Creation – Standard Build* | < 1 Hr | 99.50% |
Moves and Changes – Standard Build* | < 1 Hr | 99.50% |
Endpoint Creation – Resilient Build# | Timescales On Application | NA |
Moves and Changes – Resilient Build# | Timescales On Application | NA |
*Any non-standard manual builds are excluded from this performance measure.
# Resilient build timescales are agreed on an individual project basis, due to the variability of individual customer designs. These lead times are dependent on Gamma receiving all necessary information from the Channel Partner to enable the order progress.
Note: Service credits are not applicable against Service Provisioning performance metrics.
Note: Service Provisioning timescales for services that may be associated with the SIP Trunking service, such as Number Porting or IP Access, can be found in the associated SLA for that Product or on the Gamma Wholesale Customer Service Plan, posted on the Partner Portal.

