«ETSI TR 102 021-5 V1.2.1 (2010-12) Technical Report Terrestrial Trunked Radio (TETRA); User Requirement Specification TETRA Release 2.1; Part 5: ...»
Implementations of interworking and roaming should pay particular attention to the following aspects:
• Minimum impact on operational costs.
• Maximum transparency to the end-user.
• Minimum impact on network requirement.
• Co-ordination of numbering across technologies.
• Co-ordination of user identities across technologies.
• Minimum impact on Lawful Interception.
• Minimum impact on billing systems.
• In recent years Internet technology has transformed the networks of the telecom operators. Due to this their main stream products and services are based on the use of IP links instead of E1 links. A carefull study is needed into the use of IP links instead of E1 links.
4.6 Timeline Interworking and roaming between different TETRA networks is an immediate requirement of users. The requirement for roaming between TETRA networks varies between user organization. Some users in the Public Safety market have a requirement in 2011. A more significant portion of this market has requirements soon after that. The study into the use of IP links instead of E1 links should be finalized before this larger scale use of the ISI.
The requirement for voice interworking between TETRA networks and GSM/UMTS or PSTN and data interworking between TETRA and IP networks has been fulfilled in the TETRA implementations and is widely available in the form of gateways.
Service roaming is a relatively new requirement. There is no strong market push yet.