Ideally, bundle your connectivity with the company providing the platform so you can avoid going over third-party networks. Also, make sure your connectivity has a business SLA: consider the revenue you would lose if you lost connectivity.
Keep your life simple! Look at providers who can offer a consolidated solution under their control. You want on person to raise support queries with.
Find out what disaster recovery options you need, what security is there to protect from fraud? Ideally, choose a cloud phone system where all of this is included.
Do your research. What company growth are you planning for? Would OPEX or CAPEX be better? Do your staff want to control their own out of office, voicemail, call forwarding and more? Find out.
Avoid smoke and mirrors – don’t get drowned by jargon. Your supplier should tailor the solution to you, and you should understand how it works, after all you are paying for it!
Look for value not the lowest price. The cheapest solution won’t be the most flexible: are you going to get penalised if your business gets bigger?
Lastly, protect yourself! Make sure your provider adheres to Ofcom guidelines for having an independent arbitration service. Consider anti-fraud and DDoS mitigation offerings when looking at your internet connectivity running alongside it.