IC Knowledge Base

Common Questions FAQs

Common Questions

For all those frequently asked questions around IPVS support and provisioning.

  • Do I have to dial 9 for external line?
  • Experiencing one way audio
  • Is it possible to have a group mailbox
  • How do I access my voicemail
  • What numbers are available
  • Calls drop after 15 minutes
  • Changing music on hold

Do I have to dial 9 for an external line?

It is common for organisations with existing phone systems to dial 9 before entering an external phone number.

With IP Voice Services this is not required, the system intelligently works out if the call is to any of the following;

  • Local IPVS extension
  • IPVS extension under the company on another site
  • Local national call outside of IPVS
  • National call in a different area code
  • International call

Any calls made between IPVS extensions is not chargeable whilst all other calls are chargeable.

One way audio

This is where either party can hear the conversation but the other cannot, typically experienced on new installs or after an upgrade of network hardware.


The most common cause is SIP ALG or SIP Session Helper which needs to be disabled for IPVS to operate.

Dropping packets

The other likely cause is dropping packets, with the fact VoIP operates with UDP error correction is not available as with TCP and so the packet is not made up, and subsequently audio is dropeped.

The most likely cause for this is the provisioning of IPVS over a dsl connection which proves to be flacky, or local interferance around the terminating hardware or faulty hardware.  To combat these issues the cause needs to be identified;

For a brief checklist look below,

  • Ensure the router is plugged into the master socket;
  • Ensure all sockets are filtered, possibly replace;
  • Run a continous ping to a destination on the Internet

ping <destination> -t

Hold control and press c to cancel.

  • Run a tracert to the same destination to see where packets are dropped
  • Raise a ticket with Tech Support to run a line test on the connection

I require a group mailbox is this possible?

There is not feature a feature on IP Voice Services, however there are a couple of scenerarios to support this;

Option 1

Configure another user without a phone on the premium package, then set the user to DND.  Calls can be routed to this user where voicemail messages are left.  Voicemail can then be retrieved by any user whom knows the dummy voicemail users extension and pin number.

Option 2

Another method depending on the users role and potential confidential material is to route all voicemail to an existing user and provide access details to all required users.

How do I access my voicemail?

For those uses whom have premium or premium plus licences voicemail is included on a per handset basis.

Local Extension

It is possible to access the voice mail system from the local handset itself.


On some handsets there are phones which have a messages button, on pressing, dials the message centre requesting a pin number.

Feature code

On every handset supplied on the IPVS platform the user can dial the local extension of the handset and the prompt will request the appropriate pin number.

Voicemail Portal

For those who are trying to access the voice mail external to the site or off a handset not linked to the IPVS a directory number specific to the site must be dialled.

When this number is dialled the user is requested to enter the extension number and then the appropriate pin number to gain access.

Once access is granted you can interact with the voice mail system as if you were local and on the system.

What numbers can I buy?

IPVS allows you to port existing numbers into the platform but also to purchase new numbers (requirement of each site). Purchasing of 01,02 and 03 numbers are possible subject to availability, certain numbers like 0207 & 0208 are now exhausted and so not available. Other non-geographic numbers like 0845 may also be available. For full details please contact us.

Calls drop after 15 minutes

Once a call is established to IPVS, if that call remains connected the platform will send a session audit message after 15 minutes.  The phone should receive this and send acknowledgement back. 

If however the port which the phones connection was assigned has changed there will be no response sent back to IPVS, or any response received by IPVS will be ignored as the port has changed. 

This is usually down to firewall/switch configuration such as NAT configuration and changing the NAT refresh timer to 120 seconds.  Always worth ensuring SIP ALG or anything affecting the data packet is disabled.

Changing music on hold

Music on hold can be changed on Premium sites only.  You will need the music on hold recording in the following format:

CCITT u-Law WAV with 8kHz, 8Bit, Mono attributes

0 (0)
Article Rating (No Votes)
Rate this article
Attached Files
There are no attachments for this article.
There are no comments for this article. Be the first to post a comment.
Security Code Security Code
Related Articles RSS Feed
Approved Equipment List v.36
Viewed 2764 times since Tue, Jul 25, 2017
Wireshark Trace for Fault Finding
Viewed 9321 times since Tue, Jul 25, 2017
Compatible Routers and Firewalls - old for reference
Viewed 2405 times since Tue, Jul 25, 2017
Voicemail in IPVS
Viewed 2425 times since Thu, Dec 14, 2017
Out of office site intercept
Viewed 2066 times since Tue, Dec 5, 2017
Diverting hunt group numbers on IPVS
Viewed 2190 times since Thu, Dec 14, 2017
Changing IPVS on-hold music
Viewed 2014 times since Fri, Dec 1, 2017
Moving or configuring a phone to a user on IPVS
Viewed 1913 times since Wed, Sep 19, 2018
IPVS Auto Attendant Message Setup
Viewed 1820 times since Wed, Dec 12, 2018
Internet Central Limited, Innovation Centre 2, Keele Science Park, Keele, Staffordshire ST5 5NH
Registered Office: Ivy House Foundry, Hanley, Stoke-on-Trent, ST1 3NR
Registered in England: Reg No. 03079542 VAT Reg No. GB 278 923 705
Contact Us |Terms & Conditions |Legal, Privacy and Cookies
All prices exclude VAT E.&O.E © 2015 Internet Central

All trademarks and logos appearing on the site are the property of their respective owners