Meet Josh Mihill, Co-Founder of Honest: The UK’s First Carbon-Negative Mobile Network

We’re not just building another mobile network; we’re setting a bold new standard for what mobile can be, for both people and the planet.

Tell us about Honest

My school friend Andy and I co-founded Honest in 2019 with the ambition to build the best mobile network on the planet. We felt the big mobile networks were taking advantage: hiking up prices every year, locking customers into complicated contracts, looking the other way when it comes to the planet… the list goes on. We were convinced there had to be a better way.

We embedded doing right by both people and the planet into Honest from day one. On the sustainability side, we’re the UK’s first B Corp mobile network, carbon-negative (removing double the carbon created across our customers’ phone lifespans), and a member of 1% for the Planet, donating 1% of revenue to verified environmental causes.

On the product side, we’re constantly raising the bar of what people should expect from their mobile network. We started off with Classic SIM, our essential everyday SIM giving the UK’s fastest 5G alongside bills that drop every month. After acquiring thousands of happy customers, we realised there were still two major problems people faced globally: bad signal and expensive roaming. So we built Smart SIM, the first-of-its-kind second SIM giving unbeatable signal on EE, O2, Three and Vodafone, plus free roaming worldwide. It quickly became our best-selling product.

Since 2023, we’ve grown our customer base more than 10x and now count more than 40,000 customers. We’re not just building another mobile network; we’re setting a bold new standard for what mobile can be, for both people and the planet.

How did you come up with the idea for the company?

There were two key factors behind the idea for Honest. Firstly, my co-founder Andy and I both had terrible experiences with our mobile networks: annual price hikes, bad signal, expensive roaming, poor customer support, to name a few. We surveyed thousands of people, and it was clear that we weren’t alone. Nobody likes their mobile network. Secondly, we recognised the disconnect between our phones and their impact on the planet. The big networks weren’t doing enough to address this.

We saw an opportunity to disrupt telecoms in the same way Monzo and Revolut disrupted the banking sector. We were convinced we could build a better network  – one that does right by people and the planet. That remains our guiding motivation today.

Tell us about your core product or service.

Our core product, Smart SIM, is the industry-first eSIM that works alongside your main SIM to give you unbeatable signal on EE, O2, Three, and Vodafone in the UK, plus free global roaming in 180+ countries.

Whenever you lose signal in the UK or go abroad, you can switch to Smart SIM in a few taps for 500+ essential apps on another available network, all from just £3.75/month with no extra costs. We developed Smart SIM to address two major challenges faced by consumers everywhere: poor signal and expensive roaming fees. After launching last year, Smart SIM became our best-selling product within just ten weeks.

Beyond that, we also offer Classic SIM, our essential everyday SIM with the UK’s fastest 5G that rewards loyalty, with bills dropping the longer you stay. Plus, Family Plans make managing multiple SIMs in a single account simple.

Our commitment to doing mobile right also applies to the planet. We’re the UK’s first B Corp network, donate 1% of revenue to fighting the climate crisis as a member of 1% for the Planet, and shrink the carbon footprint of all our customers. We’ve also moved 87% of our customers from physical SIMs to eSIMs, further reducing their footprint.

What most excites you about sustainability in the telecoms industry?

“What excites me most about sustainability in the telecoms industry is the genuine opportunity for progress, driven by both consumer demand and forward-thinking businesses. E-waste is one example of this. It’s the fastest-growing domestic waste stream globally, with more than 400 million tonnes of e-waste produced every year, yet is often overlooked. That’s why the growing shift towards refurbished handsets matters so much. We’re seeing more and more people keep their phones for longer and opt for refurbished devices when it’s time to upgrade. Those conscious choices add up and have a significant impact on reducing e-waste.

I’m also inspired by the energy and drive of younger generations. As more Gen Zs start businesses and step into leadership roles, sustainability is becoming the bare minimum. That’s pushing industries, including telecoms, to innovate and rethink how they operate, whether that’s through greener products or technologies that reduce carbon footprints.

At Honest, we’ve always seen a huge opportunity to raise the bar of sustainability in telecoms. For us, it’s not a nice-to-have – it’s a prerequisite. We believe every company should have a positive impact on the planet, so every decision we make is guided by both the impact it’ll have on our customers and the planet.”

What has been the biggest challenge you’ve had to overcome along the way?

Building a business from scratch presents many challenges, but my biggest personal challenge was burning out while building a previous startup in 2018. My response to pressure was to work harder. I ended up becoming overwhelmed, feeling isolated, and neglecting my physical and mental health.

That period forced me to reconsider my approach to entrepreneurship. Now I think of it as an ultramarathon, not a sprint. Slower periods are as vital as the short, intense bursts. I learnt to prioritise switching off and, more significantly, started therapy. That’s been integral to building a more sustainable lifestyle and mindset.

I now recommend therapy to other founders and promote that culture at Honest. We’re building a company that promises to do right by people, and that applies to our team, too. I don’t want anyone to experience the burnout I did.

What is your number one piece of advice to aspiring entrepreneurs?

My number one piece of advice to aspiring entrepreneurs is to embed sustainability into your business from day one. You don’t need to be an expert, and you won’t always get it right, but instilling that mindset into your team from the start will align decisions with your values and keep you accountable. It’s much easier than trying to implement initiatives later on.

Taking Honest down the B Corp route early, for example, offered a fantastic framework for building the foundations as a responsible business. We believe it’s the right thing to do, but being a B Corp has also offered myriad benefits to the company’s bottom line: customer loyalty and retention, differentiation from competition, and top talent attraction. I truly believe that purpose doesn’t come at the expense of profit.

What can we hope to see from Honest in the future?

We’re determined to show there’s a better way to do mobile for people and the planet. That means giving people what they deserve: ethical, innovative and straightforward SIM plans that don’t cost the earth.

As well as making poor signal and expensive roaming a thing of the past, we’re continuing to pave the way as the planet’s most sustainable mobile network. That will include re-certifying as a B Corp next year, expanding our carbon removal projects – from microbial carbon mineralisation to direct air capture – and partnering with the most sustainable suppliers. We’re also accelerating towards our target to plant one million trees. We’ve already planted over 100,000 and plan to reach our goal within the next couple of years.