Moving from ISDN 30 to SIP Trunk

[ass17]

Hi All,

 

We have a dilemma, we are moving away from ISDN to SIP for phones but we don't want to route it through smoothwall, we want to keep the phones on 100% of the time. BT will not allow us to modify the Cisco router config to go through it direct and block specific incoming traffic etc...

 

What are our options? Have you created a secondary firewall/gateway on spare IPs? We are thinking of buying either second hand Cisco router or build a custom Linux box. Has anyone done similar or offer advice?

 

Thanks

[SchoolsBroadband]

Have you thought of putting sip on a separate broadband line e.g fttc and a big standard firewall? You may also want to look at end to end qos to guarantee call quality.

 

We do all of that as standard so let me know if of interest.

 

Thanks a good luck.

 

Dave

[ass17]

Thanks Dave,

 

Don't think the budget stretches that far. We have a well designed network with QoS Voice on high priority. And all our VoIP Avaya phones are connected to 2920 HP switches.

 

When BT turn us over we need either an additional firewall that is independent of our main firewall, one reason is for maintenance and many others I'm sure.

Edited May 15, 2017 by ass17

[localzuk]

We route our SIP traffic through our Sophos UTM. Not had any issues - no noticeable latency added to calls etc...

[DSapseid]

I have my SIP running through a separate BT Infinity connection (£30ppm) which even when paying for this cost the savings on the actual calls and the line rental saved from ISDN and I'm still noticing a 20% saving per month.

[ass17]

We route our SIP traffic through our Sophos UTM. Not had any issues - no noticeable latency added to calls etc...

 

Is Sophos your main firewall or a secondary? If Sophos is you main when happens when you do maintenance on it and the phones go down?

[localzuk]

Is Sophos your main firewall or a secondary? If Sophos is you main when happens when you do maintenance on it and the phones go down?

Main firewall. Maintenance happens out of hours only - there's no-one in to need the phones at 3am in the morning on a Saturday/Sunday night.

 

My thought would be if that phone uptime is so important, maybe you should invest in a HA cluster of Smoothwall boxes? That way you can do maintenance on one and the other will take over.

Edited May 16, 2017 by localzuk

[FN-GM]

We send our SIP trunks via our perimeter firewall then through Smoothwall. No issues at all. Updates etc also happen out of hours so we don't go cutting the internet / phones off for people.

[ass17]

Main firewall. Maintenance happens out of hours only - there's no-one in to need the phones at 3am in the morning on a Saturday/Sunday night.

 

3am!! Do you get paid enough to warrant being up or do you schedule at that time hoping all is well when you wake up? [emoji1]

[localzuk]

3am!! Do you get paid enough to warrant being up or do you schedule at that time hoping all is well when you wake up? [emoji1]

All scheduled. With the number of devices we have, compared to staff, it'd be impossible to babysit all updates on all servers etc... So, scheduling is a necessity.

[ass17]

My thought would be if that phone uptime is so important, maybe you should invest in a HA cluster of Smoothwall boxes? That way you can do maintenance on one and the other will take over.

 

This option is one we have been thinking about for some time but again cost could be a few thousand.

[ass17]

We send our SIP trunks via our perimeter firewall then through Smoothwall. No issues at all. Updates etc also happen out of hours so we don't go cutting the internet / phones off for people.

 

Why not direct through smoothwall?

[mrbios]

Why won't BT change any settings on the Cisco?

 

My FreePBX box uses its built in firewall and has a direct connection from VM > ISP router with a public IP on the PBX external interface. No NAT to traverse and less components between phone system and external world in the event of any issues.

[FN-GM]

@ass17 Our network topology means all internet traffic goes via 2 firewalls.

[ass17]

Why won't BT change any settings on the Cisco?

 

My FreePBX box uses its built in firewall and has a direct connection from VM > ISP router with a public IP on the PBX external interface. No NAT to traverse and less components between phone system and external world in the event of any issues.

 

We asked them and they said no, they won't support us if we change it.