Some VoIP providers restrict who they port out to as a way of keeping you with them.
In the case of VoIPfone here is feedback on UK business forum why it is really difficult to port out from them to another telecom provider.
After a few years of using Voipfone it seems we have outgrown them - BUT I CAN NOT LEAVE!!. I do not have an IVR in place now as the Voipfone system that we use is not able to provide all of the functionality that we require. I would like a system that could handle our growth for the future with significantly more extensions / numbers / IVR systems / call groups.
Voipfone advised me that they can no longer provide the service that I require. They recommended that I find a provider using an asterisk system as this is much more customisable. I have found numerous providers that can provide the service. My problem is that I cannot find anyone to port the numbers from Voipfone. The voipfone customer service representatives are slippy as eels when I ask questions as to why I cant find anyone to port the numbers.
"We can port between members of ITSPA as stated. However if you wish to port outside if that, the gaining provider may not have porting agreements with us hence not being able to port it to them."
I have tried numerous ITSPA companies and none of them can port the numbers so I do not believe this to be true.
Voipfone then said:
"Who is the company you have contacted with regards to porting? It may not necessarily be us not allowing the port away, but the provider you have approached not having a port agreement at their side. Unfortunately it can sometimes become complicated."
You are telling me it is complicated! They just will not divulge any info to allow me to understand the process! It is simple to transfer into Voipfone though!
Voipfone then said:
"Unfortunately there is nothing we can do. Yes the numbers are ours but both parties you port between need a porting agreement. You could email porting directly however I doubt much can be done."
We can provide you with new lines and point your VoIPfone line to it.
If you are not worried about replacing your existing lines then we can provide you with a list of local geographical numbers to choose from, please contact our Support Helpdesk to find out more.