ISDN (Integrated Services Digital Network)

SRI Means SEND ROUTING INFORMATION message..its is a GSM

MAP PROTOCOL message..

it is initiated by GMSC (INTER CIRCLE or INTER OPERATOR)or

it can be initiated by MSC towards the HLR to get the

details of routing information of the subscriber for the

Mobile terminated call..

The parameters are CALLED PARTY MSISDN

CALLING PARTY MSISDN.. using this information HLR will

QUERY the destination MSC and provide the GMSC with the

MSRN number which was used for Termination

Isdn is a type of data and internet service that makes use

of digital signals running along existing copper lines to

increase the data throughput, reduce line noise and enhance

signal quality. Whereas, Internet is a packet-switched

network of interconnected computers, enabling users to

share information along multiple channels. Channels which

can be made available by using ISDN for example! That makes

the difference.