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1841 and VWICs!!


could any one please clarify this:

we know that 1841 router can't support voice terminations, but when one comes to the dynamic conf tool to add 1841 WIC/HWIC/VWIC Slot options, one finds that 1841 does support VWICs (xMFT-T1/E1 or G703...)

the question now is how it comes that 1841 does not support voice termintion while supports VWICs, aren't VWICs for E1/T1 voice calls terminations to pstn?!

Hall of Fame Super Gold

Re: 1841 and VWICs!!

VWIC (Voice Wan Interface Card) are universal cards that like the name says, can support either voice or data. So it's normal that the 1841 supports them in data only mode.

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Community Member

Re: 1841 and VWICs!!

u are right p.bevilacqua, in the description of (for example vwic-mft-xx) it is a trunk voice/wan int card. thanks

and here is 5!

can i ask u two more related questions:

1: what is the difference exactly between G703 and other T1/E1 cards under VWIC-xMFT, i know that it is a matter of interface type, but are there additional features in G703 not available in other T1/E1 cards, is it correct that G703 supports channelized E1 while others don't?

2: what is meant by DI (drop and insert)feature in E1 T1 cards, i read about it but didn't get the idea yet. could u please clarify this to me?

thnaks p.bevilacqua for ur valuable responses

Community Member

Re: 1841 and VWICs!!

can the VWIC also (for example on 2800) support both data and voice at the same time, that is some channel groups be configured for voice and others for data?


Hall of Fame Super Gold

Re: 1841 and VWICs!!

G.703 indicates and additional feature that is "unframed E1 at 2.048 kbps". Unless you have such circuits, it's of no use. All verions supports channelized E1and T1. This is good Q&A from cisco:

Drop & Insert means using the router like a TDM multiplexer to combine/decombine timeslots on different T1/E1 circuits.

Thanks for the nice rating aqnd good luck.

Thank you for the nice rating.

Community Member

Re: 1841 and VWICs!!

and is it correct that Drop and Insert can be used in case i want that 15 E1 channels for voice and the remaining 15 channels for data?

Hall of Fame Super Gold

Re: 1841 and VWICs!!


in reality Drop and Insert does more than that, it let's you have multiple interfaces doing TDM MUX, while what you have described is simple termination.

Also consider, that in E1 world, mixed voice/data applications on the same circuit are very rare for multiple reasons. First, generally telco is unwilling to do such things because are too complicated to provision and configure. Second, using E1 generally the signalling scheme is ISDN PRI, that is always on channel 16. That means you don't have much flexibility like in T1 CAS, where telco and users are quite comfortable with the concept of timeslot. So the D&I application are more common on T1 than on E1.

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