ETSI - ES 202 020
Speech Processing, Transmission and Quality Aspects (STQ); Harmonized Pan-European/North-American Loss and Level Plan for Voice Gateways to IP Based Networks
|Publication Date:||1 November 2001|
The purpose of the present document is the harmonization of loss and level planning between the Pan-European and the North American regions, with a global view and the intent that the present document may be subject to adoption by other regions, in future. An equivalent standard has been published by the North American Telecommunications Industries Association (TIA 912 ).
The objective of the present document is to specify a loss plan for IP based networks particularly suitable for use by voice gateway manufacturers operating in several European countries. The recommended loss values are based on a Pan-European analogue telephone set as specified in TBR 38  and typical European public network losses.
These loss values may not provide optimum performance in countries where the telephone set loudness ratings or network losses differ significantly from the values used in the present document. Manufacturers may need to modify their loss plans accordingly, but the principles described in the present document provide guidance on how to derive suitable loss values. A spreadsheet is also provided as an annex to assist manufacturers in determining the correct loss values.
The PBX ports referred to in the present document are as defined in ES 201 168  or TIA 912 .
The present document introduces two general principles to loss and level planning to be applied to voice gateways to IP based networks, namely:
- The gateway handling the originating entity will set the ESLR of the sending end point to 8 dB at the ingress to the IP network thereby ensuring that there is a harmonized sending level for voice calls in IP based networks.
- The gateway handling the terminating entity will adjust the loss at the egress from the IP network to achieve the desired OLR at the receiving end point (this adjustment is necessary because of historical differences in loudness levels in analogue networks and terminals in different countries).
This will enable network planners to achieve the internationally recognized optimum overall loudness rating of 10 dB
The advantage of this approach is that:
- clear and separate responsibility is established for loss adjustments for the sending and receiving entities for each mouth to ear path,
- the party responsible for each voice gateway is able to make the adjustments necessary without requiring information or co-operation from any other party, and so loss planning and adjustment becomes a local/national issue.
NOTE: The approach taken in the present document is the same as is the half-channel approach that is now well established for PBXs in Europe.
The present document applies to all kind of voice services, irrespective whether they provide:
- real time conversational telecommunication between human subjects; or
- listening-only telecommunication from a machine interface (stored speech) to a human subject; or
- speaking-only telecommunication from a human subject to a machine interface.
The present document is initially limited to voice gateways to IP telephony networks. For the purposes of the present document, a voice gateway is considered to be a device that performs routing functions between:
- telephones (analogue, digital, IP);
- public and private network trunks;
- IP based networks.