Re: Iphone 4 unable to detect Rogers cellular network.
Seeing as the seller DID say " might not get any cellular reception" It could be that the sim card reader is either damaged OR the phone was tampered with & the Antenna or sim card reader is done.
Every phone will show Bell, Telus, Virgin, Fido & other carriers. That is just there for you to press & connect to their networks. If you want. try speaking to a Apple rep & see what they can do. Maybe they can see what the problem is without charging you the cost.
You can also take the phone to a cellphone shop & tell them what is going on. They can test it with other sim cards & let you know.
Also, have you tried restoring the phone? It may be happening because of the Jailbreak. Try everything & see what happens