Advice on SIP or ISDN

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wnb

wnb

wnb

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Hi I am looking on advice on a new phone system. Currently we have two analog lines with one having ADSL. The two lines are not enough and we are looking at having ISDN so we have 4 incoming lines. The sales guy said have you thought about SIP? well now I have but I need some advice which does not come from a sales guy or a website that it trying to flog me their products.

The sales guy said that my existing BT ADSL should be sufficient for 4 SIP lines but if I wanted I could upgrade to Bt Infinity (want to do this anyway).

Two things that are important to me with regards to phones and that is:

1. Reliability
2. Call Quality

Hope some of OCUk'ers can throw some advice to someone who knows very litttle about SIP.
 
Call quality is generally fine aslong as your Internet connection is reliable.

Reliability - less reliable than fixed lines and again comes down to your Internet connection more than anything else. How important is it that your phone lines are always available? Is the cost saving with VoIP worth the risk of losing some calls every now and then?

Personally I wouldn't bother with fixed phone lines anymore due to the flexibility of VoIP solutions nowadays but I come from a technical background where managing the systems would be within my remit. I could see why for some using traditional methods would be preferred.
 
We have used both in the past. ISDN 30 is reliable. However we did have a few BT issues and the ISDN was effected but resolved quickly by BT.

SIP again works ok, but generally had a few more little niggles than ISDN from the sip provider and routing or packet issues. However insure you have a decent dedicated line for VoIP with good bandwidth (yes upload is important) and low latency, I would go for FTTC over adsl if you can get it

Don't mix it up with your standard data traffic unless you have a decent circuit and can do good quality QoS so that voice traffic isn't effected by regular data. Dedicted VoIP circuit would obviously be suggested though.

Also think about what if this goes down?

Some people use ISDN with a sip trunk as backup? Some people have the ability to re-route calls from a control panel where there number resides so they can transfer the calls to another number whilst you sort your issue.
 
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DJMK4 said:
We have used both in the past. ISDN 30 is reliable. However we did have a few BT issues and the ISDN was effected but resolved quickly by BT.

SIP again works ok, but generally had a few more little niggles than ISDN from the sip provider and routing or packet issues. However insure you have a decent dedicated line for VoIP with good bandwidth (yes upload is important) and low latency, I would go for FTTC over adsl if you can get it

Don't mix it up with your standard data traffic unless you have a decent circuit and can do good quality QoS so that voice traffic isn't effected by regular data. Dedicted VoIP circuit would obviously be suggested though.

Also think about what if this goes down?

Some people use ISDN with a sip trunk as backup? Some people have the ability to re-route calls from a control panel where there number resides so they can transfer the calls to another number whilst you sort your issue.
Click to expand...

Solid advice here. Might also get better replies in the Networking section too
 
Mr_Orange said:
I was told that SDSL would be a better bet for SIP trunks.
Click to expand...

Only because it has higher upload than adsl.Back when ADSL lines had 0.5mbit upload this would have been true but nowadays with FTTC connections it doesn't really apply (unless ADSL is the alternative of course)
 
I would like to thank everyone for their advice. The salesman already mentioned FTTC and QOS would love FTTC at work but according to the BT website I can get it but according to the BT chap its not availble yet but should be shortly.

What sort of bandwith would I need for SIP?
 
wnb said:
I would like to thank everyone for their advice. The salesman already mentioned FTTC and QOS would love FTTC at work but according to the BT website I can get it but according to the BT chap its not availble yet but should be shortly.

What sort of bandwith would I need for SIP?
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Depends on the amount of concurrent calls and codec used.

This will give you an idea of the usage for each codec: http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml
 
Going through a similar situation, with trunk side call recording, call logging and Screen popping features.
Will be keeping an eye on this thread :)

EDIT:
I was told that it will take about 60-100kb on voice per call and data is given priority.
 
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We use SIP and find it very dependable, massively scalable and great for least cost routing and the like.
We have the distinct advantage of our MPLS provider also providing the majority of our SIP circuits (actually terminated on the same circuit as our existing data, with appropriate amount of garunteed EF CAR assigned for QoS purposes should the circuit become congested).

We had teething problems, mainly related to erroneous traditional analogue based devices needing traditional analogue to operate, but we are running on SIP in all bar 5 of our 56 offices.

It's dirt cheap too, when compared to an ISDN30. If I want a SIP Trunk with 30 concurrt calls, I simply have this applied to what ever Internet/MPLS circuit with the appropriate amount of EF CAR to garuntee the quality. I reckon it's about a 75 percent saving in our case.

By the way,!we use G729 which uses about 40k if I remember correctly.

Hope this helps.
 
seems spot on this thread, isdn2 or 30 is plug and play and rarely gives you any problems. SIP usually takes a while to settle in, it mostly boils down to how decent your router / firewall is and how well your IT chap can config it.

Stick with the SIP trunk provider that company providing the phone system recommends or if thats not possible there should be a list of the approved sip trunk providers thats been tested by Samsung etc.

Its certainly picking up pace, just be aware its not usually plug, play and forget.
 
LiGhTfasT said:
seems spot on this thread, isdn2 or 30 is plug and play and rarely gives you any problems. SIP usually takes a while to settle in, it mostly boils down to how decent your router / firewall is and how well your IT chap can config it.

Stick with the SIP trunk provider that company providing the phone system recommends or if thats not possible there should be a list of the approved sip trunk providers thats been tested by Samsung etc.

Its certainly picking up pace, just be aware its not usually plug, play and forget.
Click to expand...

Were a small business and the IT guy is me, i can build pc's do basic servers and networking stuff but I have not tried to QOS and I definetly want something that will be set up and will run happy without me having to sort stuff out.
 
Salesman has been back in touch with a quote, I said that I would need 4 lines and suggested he has suggested the following

Cisco Small Business Pro Unified Communications 320 with 4 FXO - VoIP gateway -
Gigabit Ethernet - 802.11b/g/n - MAIN SYSTEM 1.00

Cisco SPA 303 IP Phone Small Business SPA 502G Cisco Communications 1 Line IP Phone With Display,
PoE, PC Port - MAIN OFFICE USE PHONES 4.00

HomePlug Ethernet Over Power Adapter

Is the above kit any good would it be sufficient for my needs? My needs are 4 lines, call attendant, ability to leave messages anything above this would be a bonus such as call logging and the ability to record phone calls. If the system goes down I would have existing phone lines as back up.
 
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