How Tones (Busy Tones, alerting tones) is generated?

[peanut]

Gents,

What's the source for the mobile tones in such situations:

when call setup in progress
when called number is busy
when network is busy

Is it generated in the mobile/ send by the network?
Wha't the trigers messages for such tones?

BR,

[plannerguy]

Hi

Everything a part of Core..it starts when hit by specific events...

Regards
Planneguy

[peanut]

Thanks for your answer, could you provide more specifications?

Regards

[jan74]

My understanding is that ring/busy tones are generated by the switch. Not an expert but I remember that from some course I was on once.

[boring]

hi guys,
all tones are generated by the CN, in 2G/3G case by the MSC of the originating/terminating parties. An MSC effectivelly is a switch

Some examples:

if the B-party is ringing, the B-party MSC generates ALERTING which travels in the backward direction and eventually appears at the A-party UE (which initiated the call)
if the B-party is not pageable, the B-party GMSC (this is the gateway MSC of the B-party operator) generates a DISCONNECT with appropriate cause which again travels in the backward direction
if the B-party is busy (already in a call) or rejects the call, the B-party MSC generates a DISCONNECT with appropriate cause which again travels in the backward direction
if the A-party is dialing a number which is incorrect, the A-party MSC generates a DISCONNECT with appropriate cause which is sent directly to A-party UE

[peanut]

It's better now, thanks for sharing

But still some questions:

The Alerting/Disconnect message does not contain how to generate the tone.
especially when the tone is not the classic one (customized tone like a song)

What's the message that contain the tone signals?

respects,

[boring]

Customised ringed tones are based on the fact that the B-party MSC is able to inject (i.e. play) the actual ringtone in the upstream direction (i.e. towards the A-party), because all traffic channels (radio and terrestrial interfaces) have been established the moment the B-party generates the ALERTING message.

Actual implementation could vary depending vendor implementation. One could be based on CAMEL (this is very simplified):
1. B-party MSC receives ALERTING, this triggers the MSC to communicate with SCP (CAMEL SERVICE PLATFORM) in order to check if the B-party actually uses customised ringtones
2. SCP communicates with tone library server and starts play back
3. SCP orders MSC to continue with call establishment (i.e. sending ALERTING upstream)
4. A-prty hears the customised tone

note: everything which is played in the upstream is always free of charge. charging starts only when B-party answers the call

Reputations greatly appreciated!

[peanut]

Thanks Boring,

I understand that ringtone is sent within the Alerting with a special encoding

Some times I hear the tone with bad quality, could I suspect an RF poor quality?

BR,