Hello! Deskphone has rebranded as ONSIM - read the blog post here


Onsim is new type of highly advanced mobile network, designed to redefine what can be expected from your mobile carrier. We put a range of highly advanced features 'on a sim' to enhance your mobile network experience. It's unified communications, but with a unique 'mobile first' approach that integrate natively into your mobile rather than requiring OTT apps.
Uniquely you can choose to display either your landline or a mobile number when you make calls. You can even display a shared 'office' number across multiple sims. The person you are calling will see whatever number you set as your caller ID and if you choose to display your landline they would not know it’s been made from a mobile. If you have a team with multiple mobiles this allows you to share the same landline for both outbound and inbound calls.
We use EE as our primary network partner but the SIM's can be manually configured to use O2 instead to resolve any coverage issues or for redundancy. Please let our support team know if you are having coverage issues and we can troubleshoot this with you by analysing your device and location.
It’s very reliable! Because we can utilise the network infrastructure and masts of both the EE and O2 networks we can offer wider coverage and better redundancy than other UK mobile networks or MVNO’s. Because our network is targeted primarily at businesses the reliability of our service is of paramount importance to us.
No! VoIP (Voice over Internet Protocol) sends your calls over the internet via your data connection and you typically have to use a third party app instead of your native dialling app. Our SIM's uses traditional GSM mobile networks to make calls the way your mobile was designed to work. Because you’re not relying on mobile data or WiFi the reliability and call quality is much higher.
No. This isn't a 'soft phone' or 'VoIP' app. Once you insert one of our SIM's you just use your mobile as normal to make and receive calls, text and use data over our network and benefit from our wide range of features we offer.
BT’s Cloud service is a VoIP service. You need to install an app on your smartphone or use an IP phone. Calls are made using your data or WiFi connection so your connection needs to be incredibly stable or you can’t make clear calls.
One net is probably the most similar service to Onsim in terms of the way it works. You are however locked into using only the Vodafone network and it’s very expensive - up to 4 times the price of our service.
A virtual landline is a landline with a permanent divert to a mobile number. Inbound calls to your virtual landline will be forwarded to your mobile but they don’t allow you to make calls from your landline number. Therefore if you miss a call and want to dial back you will be displaying your mobile number not your landline.
Onsim was built from the ground up for businesses not consumers. It’s been designed to offer a wide range of features and to simplify and streamline communication for companies.
Our SIM’s are capable of roaming worldwide but to prevent unexpected charges we limit them to our Home Zone area by default - you can request that we unblock the SIM to roam in other zones - these will be charged at per min/sms/mb charges as per our published rate-card. Our home zone (Roam like at home) currently includes the UK, EU and USA and you can use your call, sms and data allowances in those regions at no extra cost. Please note that only calls and SMS to the UK are inclusive in bundle even when roaming. Please bear in mind roaming charges outside the home zone are significantly more expensive and you are liable to pay any charges incurred. If you opt to unblock a zone it is entirely at your own risk we do not offer roaming capping on your bill as this is a business service. Please speak to support prior to travelling if you are unsure of the charges.
Yes – you can have as many numbers as you want (both landline or mobile) per SIM. This makes it ideal if you want to consolidate business numbers.
No – not all UK landlines are SMS enabled so SMS is sent from your underlying mobile number to make sure your texts are delivered correctly. If you need SMS on your landline speak to our sales team for alternate solutions.
Yes – If you need your customers to ‘press 1 for sales, two for…’ we can help you set this up on your Onsim system. Please speak to support regarding setting up your IVR. Please note that this is not available on single user systems.
Yes – you can login to our portal and setup diverts to off platform numbers. You can use our easy to follow guides here
We have a list of features here. If you have a specific requirement or need a particular feature speak to one of our solutions experts by contacting our support team.
If you're looking for business mobile handsets contact our sales team for a tailored hardware quote. We can offer mobile hardware leasing through one of our partners or you can purchase a handset from a third party. Just make sure it's not locked to another network or it won't work with our service.
It depends on your system, provider and size of your requirement. Speak to our sales team for more information and how we can integrate Onsim into your existing phone system.
Yes – we offer a twinned service that allows you to connect any supported VoIP handset to your Onsim service. This means your landline number can ring on both your mobile and your office phone simultaneously, share a voicemail and loads more.
Yes – we offer a range of mobile call and SMS recording solutions for all business and regulatory needs.
Please speak to our sales and service delivery team if you need bigger data packages or want to share data across a number of SIM's.
Yes, choose your landline number (from over 650 UK landline dial codes).
We can offer all 650 UK landline dial codes for your Deskphone Go Landline SIM.
Yes – we can 'port' (transfer) landline numbers from your existing provider to use with Onsim service. We have guides on porting numbers to us in our help centre.
When you request a SIM and choose a number we will reserve and hold your chosen number for one month. Only once you activate your SIM (including successful payment of your first invoice) is the number registered to you and guaranteed. Only after registration does the number belong to you and can be ported out of our systems. Please refrain from publishing your number (printing any stationary) until it's registered and you've tested it.
SIM’s are dispatched via Royal Mail 1st Class and usually take 3-5 working days to be delivered. (Working day excludes bank holidays and weekends).
Once you receive your SIM follow the instructions to activate it. We have guides on activating your SIM in our help centre.
Once you activate your SIM it can take up to 24 hours for it to become active.
Yes your handset must be unlocked. You can check with the company you bought the handset from if it is unlocked.
Yes – our SIM’s will work in any GSM mobile
No, all our SIM’s can be popped out to all three sizes meaning they will fit in any mobile. If you keep the plastic surrounds you can build the SIM’s back up again to larger sizes.
We have a range of plans with varying allowances to suit all budgets. If you need volume pricing (for systems bigger than 10 users) we can provide a custom quote.
We offer 1 month or 12 month pay monthly contracts. We do not currently offer a pay as you go service.
On activation you will be immediately billed a pro-rata charge for any remaining days in that month. Your first full bill (and all subsequent bills) will be charged on the 1st of each month. Call charges (over allowances) are billed 1 month in arrears. Please note your services will also be pro-rata for the first month (i.e if you have 2GB of data and sign up exactly half way through the month you will only have an allowance of 1GB until your allowances re-set on the 1st.
You will be billed via a saved Debit or Credit card. For accounts paying more than £50/month we also can accept direct debit. You must have an active, automatic method of payment saved in your account as per our terms of service.
1 month plans plans do not require a credit check for activation but we restrict premium rate, service and international calls from being made until a credit check has been passed. We may perform a credit check for 12 month subscriptions and if activation of more than 5, 1 month SIM’s are requested on an account.
Yes, you can upgrade your package at any point but please note you can not downgrade a 12 month contract within the 12 month initial term without paying out contact charges.
If you use more than your planned allowance within a charging period you will be billed at the published out of bundle rate.
You can request cancellation of your contract by raising a support ticket. Cancellation policy is as per the terms and conditions applicable for your plan.
Yes – your landline number belongs to you and you can move it to another landline provider. The right for businesses to be able to transfer their landline number is protected by our governing body Ofcom so we couldn’t stop you from moving elsewhere. Please note that if you do intend to port a number to another provider you must keep your service with us active until your number transfers to your new provider. You will need to pay for your service up until the day after you port it to prevent your number being de-activated. Porting your number doesn’t cancel your contact or contractual obligations to us. Please see our terms for more information on porting.
If you require support please raise a support ticket either via your online portal or by emailing support@onsim.uk.
You can raise a support ticket either via your online portal or by emailing support@onsim.uk
We aim to reply to support tickets as quickly as possible and tickets are usually replied to within 1 working hour (please refer to our office hours and standard sla as applicable to your contract).
By raising a support ticket. In order to resolve issues fast and speed up resolution times we ask that when raising a fault customers provide a minimum of one call example demonstrating the fault. We require the time and date of the call example and the numbers involved. If these aren't provided at the time the fault is raised there may be delays in investigating the issue.
We provide phone support to customers that have an optional phone support add-on or support contract in place. As standard, all support is via support ticket. Based on our experience, feedback from customers and the sheer number of enquiries we receive we are confident this is the best way to support our customers in an efficient and fair way.