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Adtran 908E

My Mitel EL PBX requires ISDN PRI E&M Signalling. Does the Adtran 908E support this?

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Re: Adtran 908E

I think you're misreading something. ISDN PRI and E&M (robbed-bit) are two different things, although both ride over T1 transport. Mitel probably supports both as an option and you need to make a choice. ISDN PRI is what I would recommend as it is more compatible with modern features such as caller-ID and CNAM. ISDN PRI also eliminates the post-dial delay of E&M for wink and DTMF, MF or pulse signaling. You do give up one timeslot for the driver channel signaling so your circuit will support 23 simultaneous calls instead of 24.

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Re: Adtran 908E

Thank you for the reply. I do understand the situation. There are telephony conventions that equipment manufacturers have been conforming to for years. When it comes to configuring an ISDN PRI, the usual conditions are programmed, ESF, B8ZS and NI2. The PBX manufacturers require the individual channels to have conventional signalling. This is, typically, E&M. I have over 5,000 customers and, at least, 1,000 of them have ISDN PRI. EVERY system is programmed as E&M with either E&M wink, E&M delay or E&M immediate. This is a signalling convention and the PBX is looking for this from the ISDN PRI channel to properly route the DNIS digits and the call. There are a variety of devices that take the ISDN PRI 4 wire from the carrier and, usually, act as a smart jack for central office loop-up. I have several connected to Adtran devices which can be configured for E&M signalling.

Is there some sort of specification for the 908E that details what signalling the 908E supports?

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Re: Adtran 908E

rcaman wrote:

Thank you for the reply. I do understand the situation. There are telephony conventions that equipment manufacturers have been conforming to for years. When it comes to configuring an ISDN PRI, the usual conditions are programmed, ESF, B8ZS and NI2. The PBX manufacturers require the individual channels to have conventional signalling. This is, typically, E&M.

The choices are either ISDN PRI or E&M. You can't configure both on the same trunk.

ISDN PRI is out-of-band signaling. The call setup, supervision, teardown, DNIS, etc for all user (bearer) channels is done with one dedicated driver channel.

E&M is in-band signaling. The call setup, supervision, teardown, DNIS, etc for each user channel is done within that individual channel.

The two technologies are not compatible with each other. You can have ISDN PRI where you set clocking, switch type, user/network, and number of digits on both sides of the link. You can have E&M where you set clocking signaling (wink, immediate, delay), and number of digits on both sides of the link.

There is no such thing as "ISDN PRI E&M signaling" There is ISDN PRI and there is E&M. The TA900 supports both, but not both on the same trunk because this is not a thing. Your PBX won't support it either. You have to choose one or the other. Unless giving up one out of 24 talk paths for signaling is a major concern, I would choose the ISDN PRI if your PBX supports it, which Mitel has since the original SX200D with the appropriate card. Call setup is faster and caller-ID with CNAM is supported.

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Re: Adtran 908E

Following up to my own post, the configuration for E&M is as follows:

voice trunk T02 type t1-rbs supervision wink role network

- or -

voice trunk T02 type t1-rbs supervision immediate role network

More detail here: Re: program SIP to T1 cas

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