anthony@uunet.uu.net (Anthony Lee) (09/11/89)
I have a Special Report For Service Interactions by S. J. Chin (BNR Canada) of CCITT working party XI/5 (1987). The title of the report is "Specification technique for stage 2 supplementary service interactions". In this report there was a section under the subheading Types of functional interactions. The author indicated in this section that some services are functionally incompatible. The particular example that was given involved the CFU (Call Forwarding Unconditional) and CCBS (Completion of Call to Busy Subscriber which is just a retry service) services. The example goes like this "... A user activating CFU, when being scanned/monitored for CCBS recall, will cause the scanning/monitoring to be withdrawn or abandoned." My question is why withdraw the scanning ? Why not barred the user who is being scanned from activating CFU ? There are a few more examples from this report which from first reading don't seem to make sense. If Mr S. J. Chin or friends are reading this newsgroup could they make a comment ? Are there later edition of the CCITT report floating around ? Thanks in advance Anthony Lee (Humble PhD student) (alias Doctor(Time Lord)) ACSnet: anthony@batserver.cs.uq.oz TEL:(+617) 3712651 Internet: anthony@batserver.cs.uq.oz.au (+617) 3774139 (w) SNAIL: 243 Carmody Rd, St Lucia, Queensland 4067, Australia
anthony@uunet.uu.net (Anthony Lee) (09/18/89)
I have two responses to my question on CCBS and CFU. The following is a summary of replies to my question. The original question was: >I have a Special Report For Service Interactions by S. J. Chin (BNR Canada) >of CCITT working party XI/5 (1987). > >The title of the report is "Specification technique for stage 2 supplementary >service interactions". > .... >....... The particular example that was given involved >the CFU (Call Forwarding Unconditional) and CCBS (Completion of Call to >Busy Subscriber which is just a retry service) services. The example goes >like this "... A user activating CFU, when being scanned/monitored for >CCBS recall, will cause the scanning/monitoring to be withdrawn or abandoned." > >My question is why withdraw the scanning ? Why not bar the user who is >being scanned from activating CFU ? There are a few more examples from ============================= One reply was actually from S. J. Chin: I noticed your question about CFU and CCBS, and an article by Mr. S. J. Chin. I forwarded a copy of your message to Mr. Chin, who happens to work (somewhere!!) in this building. His reply, in part, is as follows: I'm no longer working on feature interactions. To answer the specific questions below: - why CFU overrides CCBS: the 2 features are incompatible, ie cannot be activated at the same time, so one has to give way, and CFU having precedence over CCBS makes for simpler interactions and/or more 'rational' operation from the users perspective (eg the U in CFU stands for Unconditional, ie the user would expect to be able to activate the feature irrespective of any outstanding CCBS, etc). ..... swee-joo ... Daniel Zlatin ========================== My comment: Why does CFU having precedence over CCBS makes for simpler interactions ? ========================== The second reply: Someone else responsed that the reason why a subscriber wanted to invoke CFU is because he might not want to be disturbed at that particular number. >My question is why withdraw the scanning ? Why not bar the user who is >being scanned from activating CFU ? A decision based on the user's perspective. If I'm setting CFU, it's because I don't want to be disturbed. Unconditionally (hence the 'U'). .... J. Deters - jad@dayton.DHDSC.MN.ORG john@jaded.DHDSC.MN.ORG ========================== My comment: There are however other reasons why a subscriber might want to invoke CFU. For example he might want to move to a new location and do not want to miss important calls. If the subscriber did not want to be disturbed then why not set up call blocking instead ? The setting of CFU could be that the subscriber do not want to be distributed but still wants to record important calls and so have all future calls forwarded to and answering machine. If that's the case then why not have the CCBS scanning transferred to the forwarded number ? This kind of question can also arise in a PBX as well, so are there any PBX manufacturers out there who care to comment ? cheers Anthony Anthony Lee (Humble PhD student) (alias Doctor(Time Lord)) ACSnet: anthony@batserver.cs.uq.oz TEL:(+617) 3712651 Internet: anthony@batserver.cs.uq.oz.au (+617) 3774139 (w) SNAIL: 243 Carmody Rd, St Lucia, Queensland 4067, Australia
chancer@houxa.att.com (Robert C Chancer) (09/20/89)
> The original question was: > > >I have a Special Report For Service Interactions by S. J. Chin (BNR Canada) > >of CCITT working party XI/5 (1987). > > > >The title of the report is "Specification technique for stage 2 > >supplementary service interactions". > >....... The particular example that was given involved > >the CFU (Call Forwarding Unconditional) and CCBS (Completion of Call to > >Busy Subscriber which is just a retry service) services. The example goes > >like this "... A user activating CFU, when being scanned/monitored for > >CCBS recall, will cause the scanning/monitoring to be withdrawn or > >abandoned." > >My question is why withdraw the scanning ? Why not bar the user who is > >being scanned from activating CFU ? There are a few more examples from Having worked on Stage 2 descriptions in CCITT and have some understanding of the implementations of CCBS being described I may be able to shed some light on the subject. Call Completion to Busy Subscriber may be totally implemented in the originators switch. It would only poll the other switch to see if the Called party is busy. The destination switch would have no knowledge of the timers for CCBS or possibly even that CCBS was invoked. So, if a user at the destination switch wanted to invoke a service, such as CFU, it would allow it. If CCBS is implemented by the destination switch, via a message from the originating switch to implement, then this info could be used to disallow CFU. One ot the things being strived for in CCIT is a consistent service view to the customer, you cannot have the service be different depending on the implementation, so CFU takes precedence. Bob Chancer houxa!chancer