MD110 Speech path

[TBLuk]

Does anyone know when an MD110 opens up the speech path?

When going over DPNSS, most PABXs don't open the speech path until a NAM or a NIM is received, but on some BC10 MDs that we have, the speech path appears to be opened immediately after an SSRM is sent.

Is anyone up for the challenge of finding this out?

 

[FICRI]

Hi,

There are several factors that can be involved regarding switch through. Signalling system used is also of importance.

Here are some examples when switch through can take place:

- after the minimum number of digits that forms a complete external number has been sent
- after reception of a seizure acknowledgement signal
- directly after seizure of an outgoing line
- after reception of the B-party´s answer signal

 

[TBLuk]

Ficri,

Many thanks for your response, but I need a definite technical answer.

I am aware that switch through can occur after your given scenarios, but I need an answer in my given situation.

As said, this is a DPNSS network, and the speech path (at least in the receive direction) seems to be opened immediately after the final SSRM is sent. The reason this is strange is that this is an SSRM(I).

In DPNSS networks, the speech path is not normally opened up until after either a NIM or a NAM is received by the 'A' PABX.

 

[FICRI]

When switch through is to take place is controlled by the SIG parameter in route data. Have a look at position D8. Perhaps D8 does not have the same value in all nodes in the DPNSS network since you seem to be getting different behaviour in different nodes?

If D8=0 you get switch through when minimum number of digits has been sent. Minimum number of digits for the specific external number (within the DPNSS network) is specified in NA and printed with NADAP:NUMTYP=NL;
If minimum number of digits for the external number is specified to a value shorter than the complete number this will result in switch through during dialling and can seem to happen when you receive an SSRM(I).

You say that the final SSRM is an SSRM(I) and I agree that this is strange. It ought to be an SSRM(C).

Other values of D8 will result in other switch through conditions. If you don´t have access to any information regarding the SIG parameter let me know. Still got your e-mail address.

 

[TBLuk]

FICRI, thanks.
I'll have a play with the SIG, ROCAC never even crossed my mind to be honest.

When these weird problems occur, I too often jump in looking through all my pathes rather than looking at the simple option!!