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Reply To: AS5300 -with Ericsson AXE-10

Matthew Webster

Hi Nick,

There could be a few issues here, but as you will know the full picture I’ll attempt to give you the right information.

1. The called party number TON (Type of Number) is ‘national’. This normally takes the form NDC + SN where:
i) NDC = national destination code (or similar). This means the area code of the number you are calling – for example, for London, UK it is ’20’.
ii) SN = the actual number of the subscriber, and follows immediately after the NDC. It can vary in length, depending on your carrier’s subscriber numbering plan. For example in London, all SNs are 8 digits and start with a ‘7’ or an ‘8’- e.g. ‘7515 7297’ or ‘8940 6723’.

What it does NOT include is the access code you dial to get to London, which within the UK is ‘0’.So, 020-xxxxyyyy would have a TON of unknown, as ‘020’ is not in national format. National format is the ‘NDC’ + ‘SN’, so the number, in national format would be 20-xxxxyyyy.

Depending on the access digits and NDC you may be dialling an ‘unknown format’ but telling the AXE it is in ‘national format’. This can cause the call setup to fail.

All this is irrelevant if you’re dialling a local number and don’t need to include the NDC. In that case, your TON should be ‘unknown’ (I think), as the number isn’t in the form NDC+SN.

2. The Bearer capability looks OK, although if you’re making a speech call, then it is normal to use an ITC of ‘speech’, instead of ‘3.1kHz’ audio. This can also cause problems at the switch, and is a popular area where calls can get rejected in the setup phase.

All said, though, I looked at the release cause you are receiving from the AXE: 0x82AF. This is better seen in binary:
82 = 10000010. The first bit is the ext bit. The next two bits indicate the coding standard, which is CCITT. The next bit is reserved. The next four bits are the location ‘public network serving the local user’, which makes sense.
AF = 10101111. The first bit is the ext bit. The next seven bits indicate the cause code reason, which in this case is “Resource Unavailable, Unspecified”.

This cause code comes from the AXE block PHPA – the block that handles Layer 3 protocols (within the subscriber control subsystem, traffic control for ISDN section). There is also MHPA, which builds and decodes Layer 3 information
in the same subsystem. This cause code could be generated because the switch doesn’t have the resource, or, type of resource you are asking for in the bearer capability (BC) part of your setup message.

I’ve found a Cisco link which tells you how to change the BC values to speech when setting up these types of calls: