Configuring toll bypass USA to UK 1

[9mmgeek]

We just set up an office in the UK that is on our phone system and I configured toll bypass by routing UK bound calls through the system there. I got it working but only by doing something I thought was wrong.

When we dial the UK from Dallas we do not dial the leading zero (0) in front of the city code. People in the UK need to dial it (I think, at least thats what I was told). So when I route a call to the UK through ARS I was stripping the 01144 and inserting the 0 to make it look like a locally sourced call. I kept getting a message about the number not being recognized. I traced it then tested with a phone that was in the UK dialing zero and it worked. The trace looked exactly the same as the other call that failed. Then I stopped inserting the (0) and it started working.

Can anyone explain how this is suppossed to work?

 

[mattKnight]

If you call any national number number (Bradford for example) from the UK you will dial 01274 xxxxxx. Th leading 0 is classed by the carrier as a trunk access code (but don't confuse with the TAC of the trunk group or the FAC to access ARS ). In fact, OFCOM number allocation documents show the area codes as 1XX i.e. without the trunk access code. International calling, as you observe, requires the international access code, country code and area code (but without the trunkaccess 0) hence the 011441274.

I'd hazard a guess that the reason your call fails is the numbering scheme; UK ISDN lines use PUB-UNK almost exclusively.

Take Care

Matt
I have always wished that my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone.

 

[9mmgeek]

Thanks Matt,

Your explanation matches what I expected but it took me a while to understand the last sentence. I did not realize the pubu in the arx table was public unknown. I use the public unknown table to set caller id. It works now with the ars call type pubu and the route inserting the 0, and it still works if the call is not routed to the UK system (the fallback scenario).

What I still don't understand is why it worked without the tac of 0.

 

[mattKnight]

Refering to the Q.931 protocol guide, for the "Called Party number" element of the call setup ISDN message gives...

Type of number (octet 3) (Note 1)
Bits
7 6 5
0 0 0 Unknown (Note 2)
0 0 1 International number (Note 3)
0 1 0 National number (Note 3)
0 1 1 Network specific number (Note 4)
1 0 0 Subscriber number (Note 3)
1 1 0 Abbreviated number (Note 5)
1 1 1 Reserved for extension
All other values are reserved.
NOTE 1 – For the definition of international, national and subscriber number, see Recommendation
I.330 [18].
NOTE 2 – The type of number "unknown" is used when the user or the network has no knowledge of the
type of number, e.g. international number, national number, etc. In this case, the number digits field is
organized according to the network dialling plan, e.g. prefix or escape digits might be present.
NOTE 3 – Prefix or escape digits shall not be included.
NOTE 4 – The type of number "network specific number" is used to indicate administration/service
number specific to the serving network, e.g. used to access an operator.
NOTE 5 – The support of this code is network dependent. The number provided in this information
element presents a shorthand representation of the complete number in the specified numbering plan as
supported by the network.

The change of number type to "Unknown" on the CM cause the bits 7, 6 & 5 to be all cleared to 0 from some other (as yet not known value) and note 2 applies - particularily e.g. prefix or escape digits might be present.

The other feasible values that you had set (international and national) mean that note 3 applies NOTE 3 – Prefix or escape digits shall not be included.




Take Care

Matt
I have always wished that my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone.

 

[mattKnight]

But I am glad it works - even if my suggested explanation is a bit obscure (and I can't be sure it is correct).

Take Care

Matt
I have always wished that my computer would be as easy to use as my telephone.
My wish has come true. I no longer know how to use my telephone.

 

[9mmgeek]

Thanks again Matt,

 

[98Converter]

You may want to confirm your calling rates in the UK... We did this, and ran into a situation where we were paying $0.03CPM to call the UK from the US, however if you placed a local call in the UK from the office in the UK the rate was higher... Therefore costing us more money - not only CPM, but added BW on our WAN. Plus it started pulling from our contracted commitment for our Service Provider in the US.

I think Toll-Bypass was useful a few years ago, but now with such competitive INTL rates, it may be better to use it a method of Business Continuance.

Just my opinion.



Thanks,
98C

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