I am at the start of putting together a proposal to move our entire telephony over to an Asterisk based solution and am keen to get some hardware & general network/topology advice.
- Our existing physical setup:
- We are a small company - total 7 employees.
- We have a UK main office and two UK satellite offices.
- We have one Italian satellite office.
- We have one Estonian satellite office.
- Each satellite office is staffed by only one person.
- We are a brokerage and consequently both make and receive significant amounts of calls throughout the day, often international.
- Our existing telephony setup:
- We have a PBX at the UK main office (BT Versatility). This has 3 analogue lines attached to it (all share the same number). We also have one 8Mbit DSL broadband line which doubles as a fax line.
- Each satellite office has a single analogue line with their own local number. These offices also have 2Mbit+ DSL broadband (attached to the analogue line).
- Desired Voip setup:
- Asterisk box (debian based) located at the main UK office, using a PBX trunk from www.gradwell.com to receive incoming calls and originate outgoing calls onto the PSTN network. We would migrate our head office number over to Gradwell.
- All staff throughout the company are given Polycom SoundPoint IP 430 phones.
- The Polycom phones and Asterisk box at the UK main office sit on their own internal LAN which is connected to a dedicated broadband line for connecting to the PBX trunk provided by Gradwell.
- The Polycom phones at all the satellite offices are connected to the internet via DSL broadband and also connected to a standard PSTN analogue line.
- Incoming calls to satellite offices originate on the analogue PSTN line, however, it must be possible for a call to then be transferred via SIP to any other office.
- Outgoing calls from satellite offices can go out via the local analogue PSTN line, however, it would be nice if they could go out via SIP to the Asterisk box in the UK main office (for auditing) and then onto the PSTN network via the Gradwell trunk.
- Further down the line we might get international numbers added to our Gradwell provided PBX trunk so that all incoming and outgoing PSTN calls from any office (main or satellite) are first routed via SIP through Gradwell and then onto either the PSTN network (if outbound) or to our Asterisk box (if inbound). In this case the local analogue PSTN lines (which are plugged into the Polycom phones) simply would act as redundancy in the event the PBX trunk or broadband goes down.
- As you no doubt will have guessed, I am very new to Voip and Asterisk - does the above even make sense? Is what I describe possible?
- Is the SoundPoint IP 430 the right phone for the task or should I be using something else?
- I presume that because all PSTN tasks will be handled by either Gradwell and their PBX trunk or the Polycom phone, it will not be necessary for us to fit our Asterisk box with any Digium cards i.e. we do not need to terminate any lines locally. Is this correct?
- Is it wise to use a PBX trunking service like that of Gradwells or is it better to have multiple analogue or ISDN lines at the UK main office and handle everything ourselves?
- From what I have read it would seem that a dedicated DSL line (8Mbits down / 512Kbps up) should be sufficient to handle 5 simultaneous calls. Is this realistic?
- I am aware that Voip is renowned for echo problems and low volume. Will using a PBX trunk service alleviate these problems or is it better to do everything internally with decent hardware & cards. Call quality is paramount to us. Cost is a secondary issue.
- That’s all (unless you spot some glaring omission I need to factor in/consider)!
I apologise if this has already been covered but I have been unable to find any FAQs or previous posts that specifically fit our scenario.
Many thanks for any and all input!