02 network down or bad phone?

for about the last 2 weeks my phone seems to be losing the o2 network signal ,have to switch off phone and then switch back on ,then the signal is back full strength, is there a problem with the network or is my phone acting up /dying

02 was down for considerable time 12-15hrs at a time over 2 outages roughly about 2 weeks ago,these outages also impacted on 48 and tesco networks.However what you are describing may be the phone.How old is it?

thanks knuttell ok now ,guess it was the o2 network