SIP2SIM®: Putting you in control of your office mobile

Mobile Voice (SIP2SIM®)

A new way to use a mobile phone

Our SIP2SIM service provides new ways to use a mobile phone...

Order now

Example Uses

Here is where you may find a use for SIP2SIM®

Sole trader - work number

Don't want to put your personal number on your van?

Using the dual SIM feature in many phones you can add a second SIM, or more likely an eSIM, with a separate service and number.

Easy to have a work number on your phone, separate ring tone, recorded calls, set contacts to call/text from work number automatically (a feature on iPhones).

It does not even have to be an 07 mobile - why not have a proper local phone number to engender trust as a local tradesman?

Find out more about dual SIM working.

Man with a Phone

Employees have the same extension at desk and when mobile

Some people spend as much time out on the road as in the office. By using a SIP2SIM®, your extension number can be set to ring both your desk phone and the mobile, making it easy for customers and colleagues to contact you.


Ensure Mobile calls are recorded

As the SIM has the same feature set as any other SIP phone connected to the PBX, then features such as call recordings are also possible. Ideal for solicitors, those in the finance industry and others, whose regulatory requirements ensure they have a copy of their phone calls.

Temporary number

Adding an eSIM to a modern phone is quick and simple.

We can issue a number (landline or 07 mobile) and eSIM within minutes (paid with order).

  • Lost dog?
  • Applying for a job?
  • Placing an advert?

We can do a service for as little as a month, or as long as you need. Even if you keep the number, you can simply disable the eSIM when not needed (still has month charges in that case).

Find out more about dual SIM working.

Your new home phone

With the demise of old fashioned phone lines, why not move your existing landline number to your mobile phone.

Either as you main phone service, or an extra number on your phone using a second SIM or eSIM.

Our VoIP service allows porting in your old number, and our SIP2SIM® service allows for that to be used on your mobile phone.

Of course, we can also provide an old school phone for your home on the same number, or DECT cordless, working at the same time as your mobile. But these days so many people use just a mobile phone. This is perhaps ideal where mobile coverage is poor inside your home.

Our SIP2SIM® service is available as an eSIM or a physical SIM card. eSIMs can be used in modern phones whilst physical SIMs can be used in an older phones.

The service uses 4G/5G VoLTE, but can normally fall back to older 2G services.

The service can work just like a normal mobile phone with calls and texts.

The service can also work by making that phone appear as if it is a SIP extension (e.g. SIP phone) on your own VoIP PABX or the a VoIP service.

We can provide our usual telephone services and a UK landline or 07 mobile number, along with all the other benefits of our service such as call recording etc.

Technical Information


Roaming throughout the EU, and US, is included (for up to 3 months in any year) at no extra cost. Other roaming is not planned, sorry.

Data allowance

We are offering a SIM with a high usage data package for £35.00 +VAT. The way this is sold to us is that it is unlimited but with a fair usage limit that we understand to be 100GB/month. When reached the service is throttled to a low speed, but one that should be sufficient for text based messaging apps to continue without problem.

The data package also allows limited hotspot functionality, 5GB/month, after which hotspot usage is throttled in the same way.

We may, in the future, be able to offer some lower fixed usage limited packages.

Note that data is always billed to end of current calendar month when adding data, and then in whole calendar months. i.e. removing data mid month does not remove data until start of next month - and then cannot be re-enabled until the month after (sorry, silly, I know, but that is the way it works).

An overview of SIP2SIM®

Not a mobile app!

SIP2SIM® is not a SIP app running on a smart phone over mobile data or WiFi! Having tried to make this work reliably, this was determined to be unpredictable at best, and completely useless at worst.

With this service your mobile phone is working as a mobile phone on the GSM mobile network using 4G/5G VoLTE; making and receiving proper mobile voice calls. GSM is a very mature technology, adept at handling changeovers between masts and packet loss, without breaking up.

And with most modern phones this can be a second line on the phone, ideal for home/work usage on one mobile phone. Find out more about dual SIM working.

Simple SIP2SIM iagram

It's just a (mobile) SIP device

The SIP2SIM® service makes your mobile work like a SIP device connected to a SIP phone system or VoIP provider of your choice. It can also be supplied pre-configured to an A&A VoIP number making your mobile work like a normal mobile phone but with a landline-style number.

Pricing Overview

eSIM £1.00 +VAT Learn more

Immediate issue of eSIM QR code

£1.00 +VAT per eSIM
SIM Card £5.00 +VAT Learn more

To purchase the SIM card (+Postage)

£5.00 +VAT per SIM
Monthly (no data) £10.00 +VAT Learn more

From when SIM/eSIM issued

£10.00 +VAT per month
Monthly (with high usage data package) £35.00 +VAT Learn more

From when SIM/eSIM issued

£35.00 +VAT per month
SMS/Call Airtime None Learn more

There are no additional airtime charges for calls or SMS to/from the SIM/eSIM in UK, EU, or US to your SIP service provider. Your VoIP service provider (eg A&A) will usually charge for the outbound calls and SMSs you make.

None call/text

An extension on your office phone system

The basic service allows you to specify, via our control pages, the server name, login and password for a SIP server. This could be your office phone system; an asterisk box, 3CX, FireBrick or similar.. As long as it handles normal UDP SIP with G.711 A-law audio then the service will register to it as a phone and allow calls both ways.

This means your mobile handset becomes an office extension, like any other.

  • Call office extensions using short extension numbers from your mobile phone.
  • Office policies on callable numbers, such as premium rate, enforced like any other extension.
  • Office voicemail system working, just like any other extension.

(Note, CLI shown on mobiles may be limited due to recent OFCOM rules)

  • Office call logging, just like any other extension.
  • Office call recording, just like any other extension.
  • Use in hunt groups, just like any other extension.
  • Even use features like call steal to transfer calls if you want, or in-band DTMF to control call transfer and related features.

Further Information

Below is further information about the service:

  • The SIM/eSIM has a cost to purchase / issue.
  • There is a monthly ongoing charge, which can be for just voice/text or some higher charges with a data package - this applies from when issued even if you have not installed the SIM or activated the QR code yet.
  • Calls/SMS to/from the mobile phone in UK, US, or EU, have no airtime charges. Roaming outside UK up to 90 days a year. A fair usage limit of 10,000 min/month and 5,000 SMS/month apply.
  • If you connect to a SIP/VoIP service (the default is A&A VoIP service), any call/SMS charges made by that service apply as normal, the same as if using a SIP handset.

When ordered, the SIM has no data allowance. You can change this at any time from the control pages, even right away. Your first month's data allowance and price for that allowance will be pro-rata to the end of the calendar month.

  • If increasing, you are charged the difference in price, and are allocated the extra data allowance for the calendar month. If it is a new SIM, the partial month price and allowance applies from when the SIM was activated in the month.
  • If decreasing, there is no charge and no change of data allowance - the change takes effect from the next calendar month, starting that month with the newly selected data allowance.
  • Note that increasing after decreasing, in the same month, only has an immediate change and cost if increasing above the actual current allowance, otherwise it is just adjusting how the next month will start.
  • Unused data is lost, this is a capped - per month - data allowance for a monthly price.
  • We hope to include an unlimited data package at some point, which may have some hight fair usage limit.
  • If you are not billed on calendar months, any change will credit or bill to ensure your billing is to the end of the current calendar month, before applying any needed adjustment. Your next bill will then be from the start of the next calendar month and resume to your normal billing cycle from there.

Calling 999 and 112 is possible.

Learn More

The service involves entering SIP registration details in to our control pages. Where these are the details of your own SIP server such as an office phone system, you can make the decision as to whether or not you trust us with those SIP details in order to provide the SIP2SIM® service. We will, of course, use all reasonable skill and care to ensure the details remain confidential and are not disclosed.

We have, however, designed the service so that it can work with a wide variety of third party SIP services, not just in the UK but in various countries. There are a lot of unusual systems out there and we continue to work to ensure that such services operate with SIP2SIM®. However, using third party SIP details may well be in breach of your terms with the third party SIP provider as it means giving us your SIP details. It is up to you to check the terms and we would not suggest anyone breaks a contract they have. You may find that the provider is happy to trust us, especially if they do any other work with us, so it is worth asking. We are also happy to discuss contracts with other providers for the SIP2SIM® service and we may be able to provide them with branded SIMs to sell to their customers.

Unfortunately we cannot guarantee that the service will always work with all other providers, and whilst we aim to resolve any technical issues (with reference to the standards), if a provider simply will not deal with our service and blocks us there is little we can do.

Branded SIM

Our voice and data SIM cards are ideal for a corporate network or for a wholesale customer to set up their own mobile service.

We can offer branding with professional quality SIM printing and pre-set settings.

Find our more

Technical details

We have a page with comprehensive list of technical details and restrictions and further articles in the knowledge base article which can be seen below.

Contact Sales

phone 03333 400222
(Mon-Fri 9am-5pm)
sms 01344 400222

Contact Support

phone 03333 400999
(Mon-Fri 8am-6pm,
Sat 10am-2pm)
sms 01344 400999